Not enough information to be certain, unfortunately, but both ‘systems’ may be suffering from duplicate IP addresses. Either set up reserved IP addresses for them in the router, or unplug them from power, then reboot the router(s) they connect to. Give the router(s) a couple of minutes to reload and reboot, then plug back in your Sonos. 

However, if this doesn’t help, I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem on each system, 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.

Thanks Bruce,

I'll give it a try next week 

Jason 

If it does ‘work’, I’d take the time to set up reserved IP addresses for at least all your Sonos devices in your router. The above procedure temporarily fixes that, but if the router has previously gotten into a ‘bad’ state, it could again. Reserving IP addresses protects against that possibility. 

Providing ‘hard’ data to Sonos is always, I think, a good thing. We in the public make guesses, as we don’t have access to that data.