Without more information about your issue, it’s pretty hard to tell. 

I’d start with a simple WiFi refresh, by unplugging all Sonos devices from power. While they are unplugged, reboot your router. Once the router comes back up, plug back in the Sonos devices.

This forces both the router and the Sonos to reboot and reload all software, and distributes all new network data through the system. 

However, if this doesn’t work, I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it, or post the diagnostic number here for a Community Moderator to pick up.

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. 

Thanks Bruce! I will try your suggestions.