I had a chat on then phone with Sonos support.
For me at least, it turns out it was my private VPN in my router that was causing the Sonos speakers to not be able to communicate with Sonos cloud.
The tech support person told me that they couldn’t see my speakers online (even if they were) through a couple of diagnostics that we ran.
He pointed me to the Sonos “incompatibility” page, where it states that Sonos doesn’t work with a VPN.
Therefore, I put my speakers to my VPN router’s exempt list, and ever since (2 days now) they seem to be working fine. No “Something went wrong message” since, so I trust this did it for me.