WiFi works but after short period all internet access ceases

[sm1ng]

Hey,

happy Essential owner here... except since a few days ago when seemingly out of the blue, my phone stops being able to hit all and any internet sites after about 5 minutes (or perhaps after auto-lock?). I can however still hit the router's http admin page. Really weird. I've checked the router for bandwidth limits etc. and all those settings are all off (and always have been).

The router is an up-to-date TP Link Archer C3200 which I've never had any problems with, and I have a lot of different devices. No other device is experiencing this issue.

On the router I've tried :

• disabling "Smart connect" (which, when a device connects, the router picks the least-busy channel channel)
• disabling IPv6 on the router
• connecting to 5Ghz only
• connecting to 2.4Ghz only
• restarting the phone
• restarting the router
• disabled "Turn on wifi automatically" on phone
• reset the phone's network settings
• fully rebooted (waited 30s) the router
• disabling developer mode on the phone
• assigning a dedicated IP for the phone on the router

and it's still happening. I'm stumped. Anyone else seeing this? The phone is running Android 9 (Pie), build PPR1.181005.034.

Any and all help appreciated.
Pete

 

[Athanasius]

Aha! This sounds like what I've been experiencing for the last 5-7 days.

Pixel 2 XL (128GB), on the 5 October 2018 patch level. WiFi initially works and then suddenly stops.

I notice it usually on new connections, such as opening Instagram and trying to refresh. I'm not 100% sure it also affects on-going connections.

My home setup is a little esoteric:

PlusNet WAP/router used only as a WAP, connected to...
A Netgear GigaBit ethernet switch, connected to ...
My home server, a PC running Debian stable (stretch). This has a separate NIC that then connects to an old BT OpenReach VDSL modem into which the phone line goes.

Since the issue started all three devices have been rebooted, and the issue remains. There are no firewall rules that would be affecting my phone, and they certainly hadn't suddenly changed a few days ago. To be sure I've just put two new FORWARD rules in to pass any traffic to or from the phone's (hardcoded) IP. And Instagram doesn't want to refresh. The moment I turn WiFi off on the Pixel 2 XL it works again.

Having the linux server/router in the mix I'm able to do packet dumps. The little I gleaned from these is it looks suspiciously like this is something to do with DNS over HTTPS to a google server. But that could just be that the obvious first part of a new connection is a DNS lookup. If I could find some way to disable this DNSoHTTPS I might be able to diagnose further.

I'm also in the middle of updating an old netbook, using the same WiFi (on 2.4GHz, but although I usually use 5GHz on the Pixel 2 XL I switched it to 2.4GHz for a while and still saw this issue). I've had no issues with the 100s of MBs of package downloads for that.

Next I need to have the phone connected over USB so I can run 'adb logcat' and see if anything jumps out at me there.

 

[Athanasius]

I'm more and more convinced this is that 8.8.8.8 port 853 DNS over HTTPS service being problematic.

I have logcat running, but nothing I can pick out looks significant.

So I moved on to pinging things from a terminal on the phone. The specific test was with "ping eddb.io" which appeared to hang, but after several minutes finally found an IP and started pinging. Right around the time the latter happened I see:

15:38:01.987800 IP 192.168.1.4.49058 > 8.8.8.8.853: Flags [F.], seq 1385, ack 3238, win 347, options [nop,nop,TS val 56438730 ecr 176096848], length 0
15:38:01.987968 IP 192.168.1.4.12103 > 192.168.1.1.53: 12706+ [1au] A? eddb.io. (128)
15:38:01.988028 IP 192.168.1.1.53 > 192.168.1.4.12103: 12706 1/5/5 A 195.154.29.187 (259)

i.e. the phone sending a FIN packet to 8.8.8.8.853, presumably because it gave up on getting an answer, and then actually using my local DNS server to lookup the IP, and getting an immediate response.

My DHCP server (on the linux server) tells the phone to use 192.168.1.1 and then 8.8.8.8, in that order. I'm going to have a play with not even telling it to use 8.8.8.8 (which I only did as a backup in case I was fiddling with bind9 on the server).

 

[Athanasius]

Took 8.8.8.8 out of the DHCP server configuration, disconnected phone from WiFi, restarted the DHCP server, ensured it hadn't remembered a lease for the phone (which might have still contained 8.8.8.8 as a DNS server), it didn't.

Reconnected WiFi, and so far it's all working. I'll report back later whether I have more issues or not. I'm now trying to find the best way to report this issue to Google, as it's their phone OS that's choosing to use DNS over HTTPS, not plain DNS, and their DNS server it's then trying to use....

 

[Athanasius]

So far no further issues on the phone \o/ . I've reported the issue here as well: https://issuetracker.google.com/issues/118036528