I'd start here, it sounds like a communications issue.

https://support.sonos.com/en-us/article/improve-your-sonos-products-wifi-connection

One note on distance, keep a meter / 3 feet between devices to avoid a "too much signal" problem.

Thank you, but the issue is happening in two separate houses with different systems and the speakers are wired. 

Would have been nice if you had shared that sooner. Good luck.

Don’t take the assumption it is the same thing in both locations. It might be, it might not. I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem in both locations, and call Sonos Support to discuss it. Don’t post the resulting diagnostic number here, they get sensitive about GDPR.

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 Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.