I have read some questions about the same issue I’m facing right now. But unfortunately I have not seen any solution yet.
The issue: I bought a pair of Sonos One, and registered them. They worked well. After a while I had to change my wi-fi network. I thoght no problem, I went through the steps advised by Sonos FAQ, and one of the speakers could be re-registered under the new wi-fi system (it is working well). But the other speaker is problematic. The android app could not see it. I can’t even go back the factory reset, since the speaker goes back to solid white led signal after every factory reset trial. So it seems the speaker is connected to somewhere but I don’t know where, and I don’t have the access to the speaker, because the application on my mobile don’t see it. Of course I have already went through hundreds of SONOS FAQs, but no one helped. :((
So what now?
Many thanks for every idea.
Best answer by Ken_Griffiths
Okay, perhaps try this .. wire the first (good) speaker back to the primary tp-link deco hub and fully close (slide off screen) the Sonos App on your mobile device. Power-off the other uncabled speaker.
Re-open the Sonos App and you should see the one wired Sonos device, (hopefully).
Then factory reset the ‘other’ uncabled speaker by following the instructions in this LINK
When the status LED is flashing green on the reset speaker, then go back into the Sonos App and goto ‘Settings/System/Add Product’ and setup up your reset speaker again by following the instructions on screen and see how that goes for you.
Once the devices are setup and working (all being well), then see what happens when you then uncable the speaker from the tp-link hub. If either speaker drops from the App when unwired then report back your findings here, but don’t opt to reset anything further, just cable the first speaker back to your primary Hub.