Apparently signing out of Apple "Media & Purchases" and signing back in can fix it in some instances on an Apple iOS device. However when I tried that and it didn’t work for me, but some users found that it worked for them.

What did work in my own particular case, was downloading the Sonos App and Apple Music App to an Android mobile device instead and adding/signing-in to the AM service from that device got it working on every device, including my iOS devices (iPhone/iPad).

So maybe give those things a try, including borrowing an Android mobile device from a friend if you perhaps don’t have one to hand.

The service has worked for me on Sonos ever since.

Sonos is unable to browse Apple Music.  (Sonos is updated.  Have turned android off and on.) What do I do?

For me this appears to be a wifi problem which I solved by doing the following:  On my MacBook I disconnected from wifi and connected to my iPhone hotspot.  Once I established a hot spot connection on my Mac I then terminated it and reestablished my normal wifi connection. Like magic Apple Music works again ( for now at least)!

Thank you ket100, I will give it a shot!