Hmm, I don’t think it will be possible to change the gateway of existing Homey devices.
When a device is added, I store the gateway PASSKEY in the deviceData to identify it so that it doesn’t appear in future pairing sessions. Unfortunately, the deviceData is read only once the device is created, so I can’t update that to the new gateway PASSKEY value.
All I can suggest is to add the device again and then use the methods here to fix the Flows:
