Not enough information to give a good diagnosis, but two generic suggestions, as it sounds like your Sonos is having trouble mainyptaining a connection to either your router, or the outside world.

First, read the wifi interference FAQ, there is a strong possibility that the answer is in that document.

Second, do a simple refresh of your network by unplugging all Sonos devices, then rebooting the router. Only when the router comes back up should you plug back in your Sonos devices.

Oh, a third thought. if you have a Sonos BRIDGE, leave it unplugged from power, and connect the ethernet cable to one of your speakers instead.

If you continue to have issues, more details about your setup, the music source, pretty much anything else would help hone in on a better answer. In fact, 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. 

You're very kind to take the time to explain that to me. I will definitely investigate all those options - thank you.