I just burned 3 days trying to figure out why I could not move 2 Sonos ONE speakers from one wifi network to another. The short story is this: Do not put a space in your wifi network's SSID name. You can stop reading now.
The long story is that I had 2 Sonos One (g2) speakers on SSID MyWifi. Then I decided to buy 2 more One's and move them all to a secondary wifi SSID ("MyWifi Guest") so my visitors could play with the Sonos app on their phones and keep them off my primary/personal wifi.
I went around in circles with Sonos support about this a few weeks ago and they kept insisting that I couldn't put them on a "guest" network. It wasn't a guest network. It was just another wifi SSID broadcast by my Ubituiti/Unify AP. No tweaks, no special treatment, just a 2nd SSID on a 2nd VLAN.
The Sonos mobile app worked fine until it asked for the new wifi password then insisted the network couldn't be found and that I had a network issue or wasn't close enough to the router. Odd how the laptop and mobile connected to the 2nd wifi just fine?
So I took the app's recommendation and connected the speaker via ethernet to a port on that same VLAN. The speakler worked fine. Then I tried to migrate to the other SSID. Same issue. The network name was displayed in the app but when I put in the password it choked and said it couldn't be found. Wait! You just showed it to me and asked me its password! What the?
So after tearing down my Netgate SG3100 router, my Netgear Managed POE switch, and the Unify WAP, and building them all back up, I decided to change to rename the "MyWifi Guest". Yes, that is an underscore.
After a few factory resets all 4 Sonos One Gen 2 speakers connected to "MyWifi_Guest" with no trouble. The moral of this story is that Sonos software has trouble with an SSID that has a space in it's name. Thanks for letting me whine