I’d start by temporarily wiring the ‘sound bar’ (what is it? Beam, Ray, Arc, PLAYBAR, PLAYBASE?) to your router with an Ethernet cable, to see if you’re dealing with some sort of wifi interference .
Next, I’d perform a network refresh by unplugging all Sonos devices from power, then rebooting the router. I would give the router a couple of minutes to recover before I plugged back in the Sonos devices. Note: if this fixes it, I’d be looking into the routers manual and setting up reserved IP addresses for at least all the Sonos devices.
Finally, if the above doesn’t fix it, 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, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network.