Seems odd, certainly. Have you submitted a system diagnostic within 10 minutes of experiencing this problem, and called 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.

Yes, it seems very strange and is very annoying. I have not tried the options you suggest but will try them before I proceed. Thank you very much for your help.

Did you get it solved via Sonos Support or are you still experiencing the issue?
I am having the same so wondering if it can be solved by Sonos?

No, unfortunately the problem is not solved yet.