I have been having problems for a few days now.
I have a SONOS one, and everything else seems to be working fine except Spotify. It started dropping out a few days ago. I have followed all the suggested ideas: rebooting router, rebooting SONOS, unauthorising and reauthorising Spotify (both from SONOS's end and Spotify's end), changing the channels of both my router and SONOS, etc. My router and one are close, because the one is plugged in, but still not that close (1.5m apart).
I can play my Spotify songs via both my IOS and desktop SONOS apps, but not via the Spotify apps. Spotify 'sees' my SONOS (i.e. it comes up in the 'Devices Available' list), but when I click on that speaker, it doesn't connect. I can actually play two different songs at once, one using the speakers on my computer, and one on my SONOS via the SONOS app, which I know I shouldn't be able to do (it's a one-person account, not a family account).
I have the same problem no matter what device I am using (iphone, PC, mac): it seems to be some kind of overall disconnection between SONOS and Spotify, not a specific app version or similar.
My diagnostics number is 2027013099
Thank you for your help