That must be rather frustrating? 
 

If it were happening to me I’d generate a diagnostics report and call Sonos support. (Since you didn’t ask for help in your statement I’m just saying what I’d do in your situation.)

Before doing that, I’d be tempted to do a simple network refresh, by unplugging all Sonos devices from power, then rebooting the router. I’d give the router a couple of minutes to come back up before plugging in the Sonos devices. 

But a solid suggestion from @nik9669a , to be sure.