Update:

I have restarted my satelite x20s and my connection feels more stable.

I noticed that the x20s were only connected, to my BE25, via 2.4 instead of 2.4/5.

Monitoring...

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My network has been stable for 9 months.

Yesterday, my BE25 updated to 1.1.7 Build 20260114 Rel. 14971 and right after my WiFi devices started disconnecting.

Wired seems to be fine/stable.

I've tried restarting my router to no avail. Really painful!