Could be any of several things, it’s hard to tell with such little information.

I’d be starting by looking at the potential of wifi interference, especially from ‘outside’ your network.
 

I’d also be looking at the potential for duplicate IP addresses, by unplugging all Sonos devices from power, then rebooting my router. Give the router a couple of minutes to finish the reboot process before plugging back in the Sonos devices.

Finally, if neither of the above work, within 10 minutes of experiencing one of these outages, I’d submit a system diagnostic, and call Sonos Support to discuss it.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network.