@john9527 did you have a chance to think what these (probably) related issues could be or what I could provide to pinpoint the issue?
It happens at least twice per week and I couldn't see any obvious reason from the logs.
Summary: my cabled linux satellite receiver going through vpn (nordvpn) just loses internet connectivity, my phones not in vpn have intermittent wifi downtimes of a few seconds per minute (both on 2.4 and 5 freq), my laptop (wifi and vpn) seems fine (although it might have the wifi issue like the phones but I don't have online games to notice it easily).
I just checked pings and although all devices can resolve google.com, only the satellite receiver cannot ping it.
Router reboot solves it and the rest of the time all works perfectly.
I am not 100% sure, but I think it started with release 23 (I use only stable).
I also flashed latest stable, formatted jffs, and restored previous backup.