I have a similar experience. Google Wifi worked fine for years. Nest Wifi Pro worked for a while.
The last several months, some of the non-primary Nest Wifi Pro devices fall off the network. Restarting, factory reseting, sometimes fixes it. But this weekend I've been able to fix it, after several hours with tech support.
Also, the last few months, Sonos speakers frequently fall off the network. It's been over a month since three of them have been able to connect. After several hours with Sonos support, they gave up.
Sometimes a phone or laptop also can't connect to the network. Restarting the phone or laptop never helps. Nor does moving around. Usually restarting the primary Nest Wifi Pro does resolve the issue. But it will come up again after a week or so.
I'm in a rural area with very little interference.
My issue may be different in that the primary Nest Wifi Pro stays online consistently. It's just other devices, especially non-primary Nest Wifi Pro and Sonos speakers, that often can't connect. The Nest Wifi Pro that drops most often is the one connected to the primary by Ethernet, which makes me think the issue has nothing to do with signal strength or interference. It seems a lot more like a software bug.
