Recently Firefox was updated to 87.0. I have noticed that every so often, in the range of 10-60 minutes, internet connection just randomly dies: no website can be opened. Note that all this time actual internet connection is up and running.
A workaround is to restart firefox. Connection comes back afterwards.
I have not experienced this problem with firefox 86. After downgrading packages to 86.0.1-1 I don’t experience this problem.
More details: the connection bug is triggered on twitch with the video player. Leaving some video to play, then switching off to another tab, after some time the video stream dies but the chat keeps coming, and I can see the viewer count go up and down, so it definitely maintains connection. If I try reloading player or opening any new tab, or reloading any existing tabs I get the usual no internet connection message. Not sure if keeping the video player in focus triggers it too.
Regarding the terminal output, every time I switch onto twitch tab I get:
It see 28 such messages in total. For the matter of fact, I use proprietary nvidia driver and export MOZ_X11_EGL=1, but I don’t think the latter has any impact.