I have 4 Amps connected in a wired ethernet daisy chain, which are then connected to a 24-port GE switch, which is in turn connected to my router. All four have static IP Addresses, appear in the router’s client list, and show up in “my system” as online when logged into sonos.com via a browser. Wireless on all 4 is disabled. However, each one at some point will disappear from the app.
I can tell when it’s about to happen. When attempting to start music via Spotify in a room, if it doesn’t start playing right away, it will hang there for a while, throwing the “selected song cannot be played at this time” error before finally disappearing altogether. I can only have it rejoin the system by power cycling the affected Amp, which is not totally simple as they’re in a rack. This has been happening since install 2 years ago and I’m losing hope that there will be a software fix.