Sounds more like a local network issue, between your speakers and the router, and not having to do with the fiber to the outside world. But the confusing part is that it’s only happening on Apple Music, and not any other music streaming services, which may point to a DNS issue between your router and the Apple servers. At the very least, I’d reboot the router, and then after that, the Sonos speakers ( unplug them for 2 minutes, then plug them back in). 

If that doesn’t resolve the issue, I’d recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it.

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

The solution is to replace Apple music with Spotify. It's a temporary solution, since Spotify doesn't reach the quality of Apple music.

There is a known issue with Apple music where it would skip even when wired. But I believe this was fixed by Sonos or Apple recently. Well mine seems to have stopped skipping anyway. All to say You might want to take a few minutes (or hours stuck on hold with support FYI) and rule out your network.

@gildor 
I’ve been playing audio from Apple Music within the Sonos App this afternoon and it’s been playing on a group of Sonos speakers and it’s been fine - I’m based in the UK though and I guess it can vary by Country/Region.

It was mentioned by Bruce earlier, but if not tried already, I think it’s still worth you rebooting your local router and Sonos players (separately). Switch off all Sonos products and then bring each player back online one at a time, starting with your Beam followed by the left and then right Era. Let each one settle and connect before moving onto the next speaker.

Doing that can sometimes help to fix some network issues.