IPv6 DNS/TLS/IMAP, XfinityConnect, Xfinity My Account apps stop working (Android)

[tzr916]

I've been having issues since November 2019 since upgrading my service to 1Gb, changing my modem to Arris SB8200, and router to Netgear R7800.

I have always been able to use an android IMAP/POP email app to check my comcast and hotmail email accounts at home when on my wifi. And I could do the same when not at home using 4G mobile data. Then when I get back home, the phone automatically reconnects to my home wifi and I can again check my email.

That last part is the problem, after I have been out using 4G mobile data, I return home, the phone reconnects to my wifi, and then the IMAP/POP email phone app fails as well as all DNS lookups- just spins never getting the new mail or DNS lookup. Plus the XfinityConnect and Xfinity My Account apps also fail.

Meanwhile, everything else on the phone works - gmail, yahoo mail, youtube, google play, etc. And all the PC's in the home work for IMAP/POP email (thunderbird), signing into my xfinity account, and email via browser. The only way I can get the android phone apps to work again is to either reboot the phone or reboot the Modem (and R7800). Then they will work, until the next time I leave my home. This rebooting action is getting extremely tiresome!

Some things that I have tried that do NOT help:
-tried several different IMAP/POP email apps and accounts/ports.
-tried switching the phone from my 2.4GHz wifi to my 5GHz wifi.
-turn wifi off / on in the phone.
-turn airplane mode on/off in the phone.
-uninstall / re-install the app on the phone.
-adding wifi to battery exclude.
-turn on "mobile data always on to allow for faster switching".
-try my GF's phone (different brand/model).

Also note, after the apps are not working on my wifi, if I connect to the neighborhood comcast wifi all the apps work! Then I switch back to my wifi and all the apps fail.

EDIT:

Seems this is related to IPv6. If I disable IPv6 on my wifi router, the problem goes away. As soon as I enable IPv6, the problem comes back. If there are some specific IPv6 DNS/TLS settings I can try in my wifi router, please let me know.

[tzr916]

Seems this is related to IPv6. If I disable IPv6 on my wifi router, the problem goes away. As soon as I enable IPv6, the problem comes back. If there are some specific IPv6 DNS/TLS settings I can try in my wifi router, please let me know.

[tzr916]

Was suggested elsewhere that the modem is blocking ports or DNS servers for TLS, so I got a DNS Lookup app for my phone and tried manual DNS servers on the phone, but it did not help!!! Set manual DNS servers on the phone for 2.4Ghz and 5GHz R7800 wifi. Reboot phone, then:
-With phone connected to the 2.4GHz R7800 wifi, successfully use DNS Lookup app to find www.google.com
-Change to local xfinity wifi, lock screen, wait a minute, unlock screen, successfully use DNS Lookup app to find www.google.com
-Change to 2.4GHz R7800 wifi, lock screen, wait a minute, unlock screen, Lookup app FAILS to resolve www.google.com
-Change to local xfinity wifi, lock screen, wait a minute, unlock screen, successfully use DNS Lookup app to find www.google.com
-Change to 5GHz R7800 wifi, lock screen, wait a minute, unlock screen, DNS Lookup app FAILS to resolve www.google.com
-repeat . . . .

Also note that I never touched the IMAP/POP email app after the reboot. Something is blocking DNS /  TLS on my android phone(s) when connected to my modem/wifi. Meahwhile my laptop on the same modem/wifi continues to work for IMAP/POP (thunderbird email client).

[ComcastChe]

Hi @tzr916, and thanks for posting. Thanks for providing a list of things you have tried that haven't worked so far. Recently there were some issues after a recent update where home networks were not recognizing the normally connected devices, which caused issues similar to what you're reporting. I want to know if you can try a few other things and let me know if there's a difference on your end. 

First, please follow this link, and then follow the process to Remove or Rename Registered Devices, then reconnect. You'll have to login again with your Comcast email address and password when reconnecting the devices. 

After you do that, can you please try setting up the IMAP/POP settings on the Android? Please let us know if there are any changes on your end. 

[tzr916]

---

@ComcastChe wrote:

First, please follow this link, and then follow the process to Remove or Rename Registered Devices, then reconnect. You'll have to login again with your Comcast email address and password when reconnecting the devices. 

After you do that, can you please try setting up the IMAP/POP settings on the Android? Please let us know if there are any changes on your end. 

---

When I click "this link", takes me to:

https://forums.xfinity.com/t5/Your-Home-Network/XfinityConnect-Xfinity-My-Account-All-IMAP-POP-apps-...

And all I get is:

HTTP Status 500 -

---

type Status report

description The server encountered an internal error that prevented it from fulfilling this request.

[tzr916]

So I found the "Remove or Rename Registered Devices" page, and deleted all devices. Then Rebooted my phone and then:

-With phone connected to the 2.4GHz R7800 wifi, successfully use DNS Lookup app to find www.google.com
-Change phone to local xfinity wifi, sign in with primary xfinity account, verify the phone is listed/ registered on the "Remove or Rename Registered Devices" page. Locked phone screen, wait a minute, unlock screen, successfully use DNS Lookup app to find www.google.com
-Change to 2.4GHz R7800 wifi, lock screen, wait a minute, unlock screen, Lookup app FAILS to resolve www.google.com
-Change to local xfinity wifi, lock screen, wait a minute, unlock screen, successfully use DNS Lookup app to find www.google.com
-Change to 5GHz R7800 wifi, lock screen, wait a minute, unlock screen, DNS Lookup app FAILS to resolve www.google.com
-repeat . . . .

SAME problem, no change. IMAP/POP/DNS is broken via my SB8200modem + R7800 wifi on my Android phone after simply leaving my home wifi for local xfinity wifi (or 4G) then going back to my home wifi.

[tzr916]

Seems this is related to IPv6. If I disable IPv6 on my wifi router, the problem goes away. As soon as I enable IPv6, the problem comes back.

If there are some specific IPv6 settings I can try in my wifi router, please let me know.