I have an Archer C7 that runs well most of the time, but periodically (every couple of days), just the 2.4 GHz signal drops out, and devices connected to it cannot access the outside world. Devices on the 5 GHz network work as normal. To fix it, I have to log into LuCi and click restart on the 2.4 interface, after which everything goes back to normal.
Where should I begin looking to figure out why this is happening/prevent it?
first thing, always include dmesg output in your bug report so we can know which kernel and driver version is in use.
then, you could post syslog output after the wlan stops working
if you feel like up to it, you could enable additional debug options for ath9k driver (these may consume quite a bit of resources)
You're not alone out there.... I and a few others have been having this or similar problems, though I havent had luck at getting much help. Have been busy lately, havent had tome to learn proper bug submittal, etc. I have saved a lot of kernel and syslog data, and would be willing to work on figuring this out, if someone who knows whats what is willing to chip in...
Circling back on this... I changed the channel to a non-standard one (ch. 3) that was less crowded, and I have not had any issues since (approximately 1 week). It would appear that something about the interference with other routers is causing the radio to shut down/stop working.
And, for another circle back, I have 16+ days of uptime, so far on a flash to the snapshot of 10-29 (ath79 version) The radio issue has not been back, no kernel warnings, etc, when it would be maybe 2-4 days till something happened. That was with 18.06.4. Oddly, I didn't seem to have the problem earlier, came after my setting it to AP only service. We'll see how it goes.
I didn't even do a full factory, just a sysupgrade with no save of settings, and that's being STRONGLY suggested as the way NOT to do it...
Once the dust settles, and I fully understand the 19.7.0, 18.06.5, vs snapshot situation, I'll probably try one of the "release" ones..