This is not a question - but just sharing my experience. I have recently updated my wifi with mesh and the older sonos components wouldnt connect despite numerous factory resets and scratching of head. Each time I went through the process to add older items - it failed at the last step when it tried to add to the LAN.
The reason was the mesh system had its own DCHP server hidden in the settings. Once this was disabled (put into access point mode) I was able to connect.
I had originally put this down to Wifi 6 compatibility
I hope this helps others