I have three Sonos zones/rooms:

Bedroom: Ray
Lounge: Arc + 2x Era 300 + Sub 3
Bathroom: Era 100

The last month or so grouping has completely broken for the Ray. If the Ray is put in a group with any of the other two zones, it will only play music for a few seconds before turning into a few seconds of white noise. Then it goes quiet and the status light starts flashing, which I would interpret as a firmware crash followed by a restart. Feels like Sonos has pushed out a faulty firmware update, but how the heck do I troubleshoot this?!

Grouping in general has been much worse the last couple of months. I've always disliked the Sonos client and typically only use it for group management, with playback handled through Spotify Connect. But the speaker groups listed in the Spotify client are almost always outdated, for example after grouping all speakers Spotify will show the group but the speakers supposedly in the group will still be listed separately as well.