Perhaps try a different WiFi channel & channel-width on your router. I suggest fixing the 2.4Ghz band to a non-overlapping channel 1, 6 or 11 and set a channel-width of 20MHz and see if that solves the issue. If applicable, do the same if running on a SonosNet signal too, but set the SonosNet channel so that it is different to your chosen 2.4Ghz non-overlapping WiFi channel. See if that resolves your grouped-rooms issue.

You can try each of the three channels on the router to see which works best for your environment, but give each one at least half-hour to settle down.

Thanks for getting back to me Ken. 
 

How do I do this? Is it something I physical attempt on my Sky router?

Thanks!! 

See this link to help get you started…

https://helpforum.sky.com/t5/Broadband-Talk/How-to-change-your-Sky-wireless-channel/ba-p/2687733

Thank you for the helpful link.

I’ve tried all 3 channels and the music is still cutting out.

Any other ideas??

Thanks.

Wait for it to happen again, submit a diagnostic and contact Sonos with the number. Calling it in is best, here may work.