I have what I think is a fairly standard setup. I just upgraded from OpenWrt 19.7 to OpenWrt 21.02.3.
After the upgrade, the connection to the website chess.com is very patchy when connected via wifi. This is a chess website, and it very often disconnects during the game (approximately it disconnects 1 time per minute, takes about 30 seconds to reconnect, sometimes it does not reconnect).
I have not other apparent problems. The connection can always be established, but just does not last.
I know it comes from the router, because if I switch to hotspot, connecting via my cellphone connection, it works flawlessly.
I tried to restart a few services, like network or dnsmasq, but it did not solve the problem.
What steps can I take to try and diagnose this problem? Are there logs I can look at? Any random idea as to what the problems could be?
This doesn't necessarily implicate the router -- it could be your ISP. When you turn off wifi on your phone, you switch to your mobile carrier, and therefore you are (probably) using a different ISP.
Have you tried a wired connection to your router?
Yes, in the main LuCI web interface > Status > System Log (or you can view this by issuing logread in the command line interface).
You also haven't given us enough information to be able to suggest possible culprits and resolutions.
Please copy the output of the following commands and post it here using the "Preformatted text </> " button:
Remember to redact passwords, MAC addresses and any public IP addresses you may have: