Things probably would have been easier if you had copied the SSID and password of the old router to the new router. Things would have connected automatically, including your One.

What you need to do now is to factory reset it again and set it up while connected to your router with Ethernet. Check for updates as well.

When done , you should be able to remove the cable and the speaker will work wirelessly.

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Unfortunately, our internet provider doesn’t let us set our own SSID or I would have done that. My system is up to date according to the app. I have the same problem whether I reset it with the network cable connected or not. Either way, choosing Update Network leads to the app trying to find the system and failing.

I just had the most ridiculous conversation with Sonos Support. I can’t update the network because my app can’t find my Sonos. Support says that it has to be connected to the wifi before my app can find it. Then how can I set the wifi password in the first place? How does it know which wifi to connect to?

Solved. I had to reset the app to clear the existing devices. Sonos wasn’t finding the speaker because it was already in the system. Very poorly thought out network management and poor documentation. You shouldn’t need to disconnect the network and remove the device just to be able to configure the wifi credentials.