In general, disconnects in surrounds is frequently due to wifi interference,  particularly in the 5Ghz area, since that’s the frequency that the surrounds use to connect to your Sonos Soundbar. 

A less likely cause could be a duplicate IP address issue, which could be cleared by unplugging all Sonos devices from power, then rebooting your router. Once the router comes back up, you can plug back in all Sonos devices. 

However, if neither of those resolve your issues, I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, 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, there are more options available beyond just the diagnostic analysis.