Sonos moderators decided to silently delete/reject/whatever my post to their forums on how to disable the WiFi on their players, so here’s a post to help all of those seeking to disable WiFi on their players.
To disable, just issue the following HTTP GET in a web browser by pasting it into the location bar:
You may have to reboot, I don’t remember. It’s been a while since I did this to mine. Of course, replace “sonos-bedroom” with the IP or hostname of the Sonos player you want to control.
If you want to disable it and have it persist through reboots, issue:
Here is the other form to turn on WiFi: