Database Develop

Help with internet sharing/tethering on Vista

OK so I thought I was halfway intelligent about all this but apparently not. I can't seem to get my internet sharing to allow me to tether on my new Tilt. I had it working fine on my Sprint Mogul so I know theoretically how to do it. I have the stock AT&T ROM (allowed customizations; just lazy about figuring out what I'd need of the customizations so I live with the bloat).
I created a shortcut for IntShrUI.exe in my \windows\start menu\programs folder to start the internet shar. I start Internet sharing and select USB and AT&T ISP GPRS (or MEdia Net; same result). It says connected and doesn't give me any errors but I can't seem to connect to anything from my PC or even ping anything. I'm using a Windows Vista PC. While internet sharing is connected I can connect to the web on the phone itself but not from the PC.
I was originally on "PDA Personal Max UNL + 1500 Messages" but I couldn't seem to connect to ISP.CINGULAR and I thought maybe that's why I couldn't tether (and I thought it'd probably prevent me from connecting to my corporate VPN). So I called in and the tech guy said that plan isn't provisioned for ISP.CINGULAR so he switched me to the "older" (his words) PDACnctUntlAdd which is the same price and includes ISP.CINGULAR but not 1500 messages. In hindsight I'm guessing that's not my problem (especially since it didn't fix it) and I'll prob go back to PDA Personal Max with the 1500 messages once I figure out the tethering and assuming it allows me to VPN.
My settings are:
AT&T ISP GPRS
Modem:
APN: isp.cingular
Username: [email protected]
Password: CINGULAR1 (doesn't show it but found that online)
Domain: blank
Advanced Settings:
TCP/IP: Use server-assigned IP Address
Use software compression: not checked
Use IP header compression: not checked
Servers: User server-assigned IP Address
Proxy Settings:
This network connects to the Internet: checked
This networks uses a proxy....: not checked
MEdia Net
Modem:
APN: wap.cingular
Username: [email protected]
Password: ????? (doesn't show it and never looked for online)
Domain: blank
Advanced Settings:
TCP/IP: Use server-assigned IP Address
Use software compression: not checked
Use IP header compression: not checked
Servers: User server-assigned IP Address
Proxy Settings:
This network connects to the Internet: checked
This networks uses a proxy....: not checked
I've tried to do it with the proxy disabled (running Disable Proxy from programs) and with it enabled with the same result.
So what can I be doing wrong? I'm sure it's something supremely stupid (if it's not a provisioning problem but how could it be that?) but I can't for the life of me figure out what I'm doing wrong.
Any help greatly appreciated and let me know if there's anything else you'd need to know to get this working.
If it matters I have the following installed:
Kaiser.HTC.Home.v2.0.814.722.HTCHome.Dir.With.Brig htness.Fix.Updated.01OCT2007-schen.cab
duttythroy HTC Audio Manager 1_2_816716.cab
duttythroy HTC Voice Recorder 1.10.1717.2221.cab
duttythroy HTC_SIM_Manager 6.31.cab
duttythroy Task Manager 2_0_30995_1.cab
HTC Touch Keyboard + Keypad.cab
Kaiser_BCR World_Card_1_0_070724b_x.cab
Vibra (Switch) 1.32.cab
ComMgr3G(10 Buttons)fixed.cab
cecmd.arm.cab (Total Commander beta 2.5 build 3)
HHCv10b5.CAB (HTC Home Customizer v1.0 beta 5)
LiveSearch.cab
Tillanosoft tGetFile.dll (for pocketnester)
Microsoft Office OneNote Mobile
RViewer.cab
Birdsoft All-in Hold-em
Google Maps

So your device says connected (and can surf the web) but your laptop wont connect?
So is your laptops firewall blocking the network?
Have you tried it over bluetooth, and use the BT PAN option. Select BT in ICS and click connect, and click YES to allow it to be discoverable, then in Vista, click start, connect to, Then click Set up a network or connection. Then scroll down to the bottom option (BT PAN). Click it and it will offer your device's BT PAN, select that and click connect.
Wait for 30 seconds, then open the web.

Solution from ATT-Connect your Laptop/PDA
Here ya go! Tried it myself with the usb. Workin good-ATT has a comm manager app that installs on the laptop.
Here's the link to the ATT support for it.
http://www.wireless.att.com/businesssupport/setupOTW.do?phone=ATTTilt
Alemaker

Thanks for your help; hadn't thought of turning off firewall since it worked with the mogul without doing that. Tried that and it didn't work. Then tried with bluetooth and that didn't work either. Didn't want to use the ATT comm manager on the off chance that they could track tethering usage on it.
And of course it was a stupid thing not to check but something made me try connecting to an IP address and not a URL and BAM! it worked. So I guess I have a DNS problem and not a connection problem.
So now anyone have an idea why the laptop can't resolve DNS but the Tilt can? Should I manually set free public DNS servers on the Tilt? Or on the laptop?

Vista you said? correct?
Try making the network that Vista sees when you connect-private; if it's public,it'll block stuff

Yeah, it's already set to private. Still no DNS resolution. I'm going to try using a free public DNS server on the PC. Strange that the Tilt isn't passing thru DNS for me but it seems it is for everyone else.
Well using the free DNS servers (208.67.222.222 and 208.67.220.220) seems to work now and it even seems to resolve DNS faster. I feel better that I figured out how to get it to work but I'm definitely confused as to why it doesn't work by default like it does for everyone else.

get tethering working yet?
hi,
i have the same issue. have unlimited data plan on my tilt. no problem with connection on my tilt (although i did not put in all that proxy setting crap att asks you to put in).
anyhow
- installed the htc modem driver on my laptop.
- turned on the modem on the tilt
- created a new dialup connection on my xp laptop
---> question here, what is the "phone number" that should be dialed???
--> for [email protected], password is CINGULAR1 also
as a last resort i will try using the att comm manager, but like you i don't really want to do it due to any tracking att may be doing...
would be great to hear if loading that local dns resolves your problem, altho it seems kinda clugey (sp?)

lol-
ya'all kill me.
Anything at all,including data; going through any major network in the U.S., is tracked- period. Cell calls,data,internet connections, and even landline calls are ALL tracked in the U.S. now. Thanks to the current administration, EVERYTHING is tracked.
Alemaker

I meant tracked in terms of tethered vs non-tethered (not being on a tethered plan; but then I tether about once a month when travelling in airports if that so I'm not worried about it). I know big brother is always watching (especially on AT&T):
http://abcnews.go.com/Politics/Story?id=3833172&page=1
@jprai I did get tethering working by just changing my DNS settings on the laptop to free servers. I'm not using wireless modem but the Internet Sharing app on the PocketPC (go to \Windows and copy the shortcut "internet sharing.lnk" to your \Windows\Start Menu\Programs directory and then you'll be able to start the app easily). It's much easier to use (well now that the DNS issue was figured out).
I'm still very curious why DNS isn't working for me with the default settings and it does for everyone else but I'm OK with this work-around for the time being.

erikk said:
I meant tracked in terms of tethered vs non-tethered (not being on a tethered plan; but then I tether about once a month when travelling in airports if that so I'm not worried about it). I know big brother is always watching (especially on AT&T):
http://abcnews.go.com/Politics/Story?id=3833172&page=1
Click to expand...
Click to collapse
Sorry for gettin us off topic with this,p but, yup^^^^), and glad ya got tethering working!
Alemaker

erikk said:
Yeah, it's already set to private. Still no DNS resolution. I'm going to try using a free public DNS server on the PC. Strange that the Tilt isn't passing thru DNS for me but it seems it is for everyone else.
Well using the free DNS servers (208.67.222.222 and 208.67.220.220) seems to work now and it even seems to resolve DNS faster. I feel better that I figured out how to get it to work but I'm definitely confused as to why it doesn't work by default like it does for everyone else.
Click to expand...
Click to collapse
This did the trick for me, thanks!
For those not fully aware of how to do this, connect your phone with ICS, go to network connections (control panel->network and sharing center->manage network connections), right click on the phone's connection (hover over them if you're not sure about which is which... mine said NDIS something or other), go to properties, click on TCP/IPv4, go to properties, and then give it the DNS addresses listed above.
Thanks!
-Taylor

Internet Sharing - Bad Connectivity

I’m here on the coast at Keesler Air Force base. There is no internet to speak of and I do not want to spend roughly $1,400 to obtain it through a Cell provider for my laptop. I setup the Internet Sharing on my TILT and it works somewhat. Well, I lied. It stays “connected” however the damn thing peers off and the laptop continuously loses connectivity.
I only use Skype and sometimes webmail with the Internet Sharing and it cannot handle it. Every minute, sometimes up to six minutes, Skype videocalls and standard webcalls are dropped and I test the internet connection to see that it’s timing out for another minute or so and then it magically reappears.
I closed all applications and the antivirus crap to ensure that there was no extra throughput bandwidth. Anyway, I’m about to lose my damn mind here because I cannot stay in contact with my fiancée who’s on the other side of the globe right now.
According to the phone I’m only getting the Edge network and that makes sense as there are not 3G towers nearby. The signal continually shifts from two bars to four bars. I have used the Kraiser Tweak to enable HDSPA but that service is not being picked up.
Any ideas as to how I can keep the connectivity from dropping between the cellphone and the laptop? I assume that’s the issue as the phone stays “Status: connected” within the Internet Sharing application.
If it matters, I can only use the "Media Net" option under Network Connections. Media Net utilizes the wap.cingular access point.
I have tried to use the "ATT ISP GPRS" option but it continually loops through attempts to connect to the internet. Eventually it gives up without any success. The ATT ISP GPRS uses the isp.cingular access point.
Please any assistance would be most appreciated. This United States Airman is about to lose is frigging mind over the fact that he can’t communicate with anyone any longer. Ugh!!!
Thanks to any thoughts and advice to better my situation...
Oh and for the record, if it isn't understood being a Tilt, my provider is ATT.

HSDPA will not work without 3G service. MEdia Net is the best way to tether, I use it all the time. Make sure the proxy option is unchecked, or you will get very poor speeds and high latency.

What do you mean by HSDPA? Also, I tried with MEDIANET but I continually lost connectivity. However, ATT ISP GPRS seems just as bad if not worse. Any thoughts on something I can do to boost connectivity? I don't know about the proxy but where I looked one is NOT enabled.
I enabled IP Compression and Software Compression for ATT ISP GPRS and it hasn't seem to have any affect...
Thanks a lot.

crypted said:
What do you mean by HSDPA? Also, I tried with MEDIANET but I continually lost connectivity. However, ATT ISP GPRS seems just as bad if not worse. Any thoughts on something I can do to boost connectivity? I don't know about the proxy but where I looked one is NOT enabled.
I enabled IP Compression and Software Compression for ATT ISP GPRS and it hasn't seem to have any affect...
Thanks a lot.
Click to expand...
Click to collapse
You mentioned HSDPA, so that's why I said it. As for ATT ISP GPRS, you do not want to use that unless you have a modem tethering option on your AT&T account. If you go under MEdia Net settings, and then check the Proxy tab, make sure the proxy option is unchecked.

Allrighty, I've confirmed that the Proxy is not enabled. The only thing on the Proxy option section that is enabled is the first option where it says this network connects to the internet.
Any ideas on stabilizing internet on a 2 - 3 bar Edge network? If I do more than one task (more than one website OR a website and Skype) the internet gets lost quite easily...
Thanks a lot man.

Wow when I was over that way I dont recall have any issues with ATT and internet. When I access the net while tethered I use the ATT program that connects via laptop... Its not the internet sharing program.... Its called ATT Communication Manager... It may read as being tethered so if you dont have tethering on your plan then I dont know if id use it. If you have tethering it works great for me. Heres a link for the download...
http://www.wireless.att.com/businesssupport/setupOTW.do?phone=ATTTilt

You might want to try flashing another rom and radio. I remember I had an issue similar to this with my hermes from ATT. Swapping to another radio can definitely boost your signal quality. If your signal drops too low even for a second, it can cause major latency issues on the edge network( which WILL cause skype to dop a call ) . I recommend trying a ROM that already has a radio packaged in with it to save you the trouble of having to match a radio to a rom. Also look for one that has the network configuration cab built in so it can automatically set up your Connection settings for you.
Hope this helps

Allrighty... I don't have much time to research ROMS or RADIOS unfortunately. Any suggestions on where to find them, or what I might use? I'd almost prefer just to change RADIOS so long as I can find the original RADIO to replace any changes back to what I was using...
Currently, I have:
ROM 1.62.502.0
RADIO 1.27.14.09
Any help to further this US Airman along would be appreciated.
Thanks.

gprs connection failed

It worked yesterday but now won't. If I enter proxy settings into orangeinternet acp the same as orangewap then it works for http traffic but not email.
I have done a lot of setting up on the phone since it arrived yesterday but I can't think what I can have altered in the gprs settings.
I had the same issue with my Touch Cruise on the newer ROMs and it went away when I reverted to the official HTC Cruise 6.1 ROM.
Any ideas anyone?

You could always try running the network setup wizard again?

You could always try running the network setup wizard again?
Click to expand...
Click to collapse
I tried that several times - it doesn't work. I think it must be a screwed setting from setting up something like exchange server in activesync.
Everything works under wifi.
I am really hoping I don't have to do a hard reset and start all over again.

Try putting a different operator's sim in and let it set everything up for it, then put your orange sim back in and go through the auto setup again. If that doesn't work then a hardreset might be your only option. Going from your other posts in the themes, applications and software it looks like your phone is really playing up so a hardreset might be best all round, only install one thing at a time and test everything after every install and customisation until you find out what you're doing to break it, then don't do that step again.

Have you messed around at all under the network advanced options where you set things like HSDPA etc

Thanks for all the replies. I've ended up hard resetting and re-customising one thing at a time.
The thing that breaks it seems to be when I change the wifi settings. I have a non-standard wireless network at home and I have to specifiy the IP address and default gateway in the "network adaptors" settings for wifi. Once I access the network with these settings it breaks the cellular data connection!
Like I said earlier, my Cruise did this as well with the later ROM such as Udk's and C_Shekhar's. When I went back to the official HTC 6.1 ROM everything worked fine.
I have now reverted my wireless settings to standard (i.e. DHCP) and it has restored the cellular connection but, obviously the wifi doesn't work.
If I can't sort this I'll have to rethink my home network.

Sounds like you're using set IP addresses on your home network for port forwarding or something of that nature. Have another look in your router's settings as most decent ones will allow you to reserve IPs from the DHCP range for specific MAC addresses, that way when the computers or other devices ask for an IP they get given the same one every time. Things really do work much more smoothly as far as networking goes when DHCP is working. If you really do need to specify IP addresses manually then just let the router hand out addresses by DCHP from a restricted range, e.g. if you manually specify addresses from 192.168.1.2 to 192.168.1.10 then set the start address for DHCP to 192.168.1.11.

Thanks, shuflie. It's actually to do with the default gateway. I have an orange livebox doing the adsl work so I can plug a telephone in to it to get free calls. However, the wireless is useless on the livebox so I have a netgear wireless router on the network as well. The trouble is, DHCP won't work that way so I have to set each wireless device up with a dedicated IP address and direct it to the livebox as the gateway.
For some unknown reason, this breaks cellular data on winmo devices.
Anyway, until I find a solution I have removed the orange livebox from my system. I'll just have to live without the broadband phonecalls which is no big deal tbh.

I actually run a non standard network here too, a SKY ADSL router to provide the broadband access and a Netgear router which all my computers attach to. Both router are set up as DCHP servers, but the SKY box only gives out an address to the Netgear router, the Netgear hands out the IP addresses for everything else. The only drawback I've seen so far is that it seems impossible to initiate a connection from the outside world to any of the computers on my network because of the dual NAT that is happening, but that isn't necessarily a bad thing as it makes it harder to hack in from outside. I don't have to point the computer and other devices to the SKY box as the gateway, I just let the Netgear router think that the connection it is getting from the SKY box is a direct connection to the outside world. Everything seems to work just fine, no problems with network gaming on the playstation network and torrents, skype, web etc. seem to work just fine. If you can't live without the broadband calls you could give it a go.

Should have said that the SKY and Netgear routers are on different subnets, 192.168.0.x for the SKY and 192.168.1.x for the netgear.

[Q] VPN issues

Hi All,
I am having issues when trying to connect to my work VPN. I need VPN access in order to check my work email and browse an internal website.
Now, the VPN always connects, either on 3G (in UK) and wifi.
However, even if it says "connected", I am not able to download emails orbrowse the intranet unless when connected to my home wifi and sometimes on mobile internet.
If connected through other wifi networks (recently tried on a hotel free wifi, in the states and on a private home network, in Croatia), the connection itself seems to go through some sort of bottleneck, and no emails or browsing is then available.
I am blaming the phone itself, since my colleague had no problems whatsoever on his iPhone.
I am on Galaxy Note, non rooted, Vodafone UK.
Please help, this issue is making my Galaxy Note almost useless.

ponch10 said:
Hi All,
I am having issues when trying to connect to my work VPN. I need VPN access in order to check my work email and browse an internal website.
Now, the VPN always connects, either on 3G (in UK) and wifi.
However, even if it says "connected", I am not able to download emails orbrowse the intranet unless when connected to my home wifi and sometimes on mobile internet.
If connected through other wifi networks (recently tried on a hotel free wifi, in the states and on a private home network, in Croatia), the connection itself seems to go through some sort of bottleneck, and no emails or browsing is then available.
Click to expand...
Click to collapse
just FYI I'm also on UK Vodafone and I can connect fine with openVPN to my home network ... tested on 2G,3G/H+ and also on various public & private WiFi networks - always connects fine, only issue I have is that my server .ovpn tells the phone to use my home router as it's default gateway (so that I can browse securely on public wifi). This doesn't work out of the box - I need to use the openVPN app's "fix DNS" option.
ponch10 said:
I am blaming the phone itself, since my colleague had no problems whatsoever on his iPhone.
I am on Galaxy Note, non rooted, Vodafone UK.
Click to expand...
Click to collapse
errr ... I'm an android noob, but AFAIK you need root for openVPN to work? I never tried running openVPN on my note BEFORE I rooted it, but anything I've ever read says root is required?

_pigro_ said:
just FYI I'm also on UK Vodafone and I can connect fine with openVPN to my home network ... tested on 2G,3G/H+ and also on various public & private WiFi networks - always connects fine, only issue I have is that my server .ovpn tells the phone to use my home router as it's default gateway (so that I can browse securely on public wifi). This doesn't work out of the box - I need to use the openVPN app's "fix DNS" option.
errr ... I'm an android noob, but AFAIK you need root for openVPN to work? I never tried running openVPN on my note BEFORE I rooted it, but anything I've ever read says root is required?
Click to expand...
Click to collapse
What APN do you use?
I have to switch everytime to something called MyLan to connect over 3G.
I am using the stock VPN client, did not adventure myself into OpenVPN. Would that work with an encrypted VPN?

Ah, sorry - I somehow managed to read the thread title "[Q] VPN issues" as "OpenVPN issues" .. case of my eyes seeing what they wanted to rather than than what was actually there. You are of course right, the stock VPN options don't need root (and of course openVPN client will only work to talk to an openVPN server).
I did set up a PPTP server on my WinXP home machine and tested that with the note's inbuilt PPTP VPN client - it worked OK although I needed to turn off encryption, and I didn't do anything with it beyond just connecting as I was only dong it out of interest.
re. the APN - I don't actually know where to see that on the note (noob, as I said!) - when I do settings->wireless & network-> mobile networks, which claims to allow setting APN's, there is no info or settings re. the APN other than the "network mode" and "network operators" items, neither of which seem to show the APN used for vodafone data access.
Anyway, sorry for the bum steer, hope you get it sorted

_pigro_ said:
Ah, sorry - I somehow managed to read the thread title "[Q] VPN issues" as "OpenVPN issues" .. case of my eyes seeing what they wanted to rather than than what was actually there. You are of course right, the stock VPN options don't need root (and of course openVPN client will only work to talk to an openVPN server).
I did set up a PPTP server on my WinXP home machine and tested that with the note's inbuilt PPTP VPN client - it worked OK although I needed to turn off encryption, and I didn't do anything with it beyond just connecting as I was only dong it out of interest.
re. the APN - I don't actually know where to see that on the note (noob, as I said!) - when I do settings->wireless & network-> mobile networks, which claims to allow setting APN's, there is no info or settings re. the APN other than the "network mode" and "network operators" items, neither of which seem to show the APN used for vodafone data access.
Anyway, sorry for the bum steer, hope you get it sorted
Click to expand...
Click to collapse
Oh, never mind
Under mobile networks you have to go under Access Point Names, but most likely you will only have one APN, which is the regular from Vodafone.
So most likely is the encryption causing problems?

D'oh ... I thought that was a heading, didn't realise it was a clickable item! my APN is wap.vodafone.co.uk (APN type is "internet+mms").
IDK if encryption is anything to do with your issues ... I doubt it if you can consistantly connect from home wifi and sometimes from 3G - if encryption were the problem I'd imagine it would consistantly connect (or not) rather than be variable.
Maybe worth trying to ping your internal mail/intranet servers when connected and then talking to your work IT guys in case there are firewall/routing settings that you are somehow falling foul of?

Yes we are doing that, however that fact that iPhones can connect really makes me wonder!

Thread Moved To Q&A​
This is a question, and as such belongs in the Q&A Section​

there are lots of third party vpn tools and free available you can use those

Wilsonj,
Can you please suggest one third party vpn tools that works well on PPTP, with encryption?
I am not looking at OpenVPN, since it doesn't suit my needs.
Thanks!

ChromeCast with RT-AC66U running Merlin Firmware

In order to get my Chromecast working with the latest Merlin flash I had to Enable the following on the "LAN / IPTV" page of Merlin firmware:
"Enable efficient multicast forwarding (IGMP Snooping)"
(If you're not familiar with Merlin version of the firmware for this router - it is essentially like the Asus firmware with some goodies / upgrades tacked on and fixes applied.)
I DID NOT enable IGMP Snooping settings in the 2.4ghz "Wireless / Professional" tab if anyone was wondering about that setting. I have limited knowledge of what these settings actually do and was just troubleshooting via trial and error.
I did a REBOOT through the router interface after setting the enabled setting in LAN / IPTV mentioned above.
Just to let you guys know as I didn't see anyone completely address it here and I was really struggling with getting my Chromecast set up on a new flash until I found this particular setting change.
I am running a pair of RT-AC66U's. (I keep one off-line that I play around with flashing Merlin and/or DD-WRT firmware and put on-line for testing purposes if something goes wrong with a flash or setting).
My version of Merlin is the latest Beta I could download at:
https://www.mediafire.com/folder/bkfq2a6aebq68//Asuswrt-Merlin#lt9d2blv8a9uh
I am using "Firmware:3.0.0.4.374.36_beta1 (Merlin build)" according to my configuration page. This is the latest Beta dated 12-23-2013.
I'd be interested in finding out if anyone is using anything different with success on Chromecast with this router configuration or if this is the only configuration that works. Haven't done any network testings of any substance yet but everything seems to be running smoothly.
Pings to my internal LAN server seem to be tight anywhere from about 1-5msec.

I run rt-n66u's and haven't had any issues but I am also not running the latest merlin.
Thanks for the post so after I upgrade if I am having issues I know what to try first.
Sent from my Nexus 5 using Tapatalk

I'm running the latest Merlin and have no issues with my cc. I haven't tweaked many if any of the router settings.

ChromeCast and Merlin firmware
Warjcowski said:
I'm running the latest Merlin and have no issues with my cc. I haven't tweaked many if any of the router settings.
Click to expand...
Click to collapse
My setup was working for a while - but after about a week or so, the setup above seemed to totally dog out my Internet connection and it was definitely something in the router as I was getting 30+ mbps download and 10-20 mbps upload which is consistent with what my ISP says they are providing to me. (Tested by hooking up my Ubuntu laptop directly to the cable modem.)
I literally couldn't run Chromecast with Netflix. Not sure why the router got so bogged down after a few weeks. So I hooked up the standard Asus firmware - this worked fine for providing Internet access at fully subscribed speeds - but now the Chromecast won't work with the most recent firmware that Asus has for the RT-AC66U. Tried IGMP snooping and it doesn't seem to matter.
I see there is a third Beta revision of the Merlin firmware - presently. I'm going to try that version on my backup version of this router and see if that presents any problem or not with the Chromecast.
Wish there was a good troubleshooting guide for CC and this router. So many settings and very little information as to what works and what doesn't when using CC with the RT-AC66U router.

Haven't had my chromecast working for months with this router now. Kind of given up. Actually not sure how I even got it set up the first time.
Must have been sheer blind luck.
A lot easier just to hook up the laptop with display port or HDMI connection and stream to the TV.

Somewhat related but I have the N66U with Tomato FW and cc not connecting for some reason. Was fine on Merlin FW

I have a RT-N66U running Merlin 374.41 build. My Chromecast was working fine until a recent Chromecast update to the 16664 firmware. Unfortunately, I did upgrade the router sometime in the same timeframe, so I don't know which is the ultimate problem. Also, I checked my "efficient multicast forwarding" setting mentioned in the OP, and it was not enabled. I will try that and see if that changes anything.
To be clear, the Chromecast seems to connect to the wireless network, but it looks like the protocol traffic is getting lost since none of the other Chromecast enabled devices on the network can see the Chromecast. To fix it, I've been having to do a factory reset on the Chromecast and go through the setup procedure every time I want to use the Chromecast.

IGMP Snooping allows/tells the router to analyze the IGMP group information of packets and handle them based on that.
This allows for more-intelligent multicast packet forwarding to specific ports rather than flooding all ports.
It's very much akin to how a network switch remembers which addresses are connected to each port and sends packets destined for that address only to that port whereas a network hub will send every incoming packet to all ports, quickly flooding available bandwidth.
Quick example case - say you have two pairs of devices communicating, A->B and C->D, all on 100 Mbps (Fast Ethernet) connection.
On a switch (assuming full switching fabric), A's traffic to B will only go to the port B is on. The same is true for C's traffic to D.
Thus, A->B traffic will have full 100 Mbps bandwidth and C->D traffic will have full 100 Mbps bandwidth (minus overhead, of course).
On a hub, A's traffic to B will still "clog the pipe" on all ports, the same with C's traffic to D.
Thus, instead of A->B having a full 100 Mbps and C->D having a full 100 Mbps, the combined traffic shares 100 Mbps.
If things are equally balanced, A->B gets 50 Mbps and C->D gets 50 Mbps, but in reality this is rarely the case.
You can also think of this like having a dynamically-created VLAN memberships for multicast traffic.
However, the potential downsides are decreased throughput and increased latency for other traffic since some processing time is required to snoop the packets. Also, if the multicast client does not properly register, or router/switch has a bug, the client might get entirely ignored and "miss" the multicast packets entirely. That's why one of the troubleshooting steps is to toggle IGMP Snooping (it's usually disabled by default, but sometimes not) to see if there is an inadvertent shunning going on.

Ok, it looks like I needed to turn TKIP back on for the 2.4GHz network. Once I switched to AES+TKIP, the Chomecast shows up again on my mobile devices.

troycarpenter said:
Ok, it looks like I needed to turn TKIP back on for the 2.4GHz network. Once I switched to AES+TKIP, the Chomecast shows up again on my mobile devices.
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Interesting situation. I run AES-only but I've seen router "quirks" like this in the past.
On some old routers I had "creeping" configuration issues where after repeated configuration changes the router would eventually lose its mind and I had to reset the configuration and apply settings by hand again. Sometimes in the "lost its mind" configuration it would do very strange things.
Now would be a good time to back up your router configuration, just in case you have an issue like I had in the past.

I have a chromecast running with rt-ac66u router with dd-wrt. if I forget which atm but the chromecast had issue with either tkip or aes. I changed it to the other and it now works flawlessly.