The instructions are in the factory reset FAQ.
If they don’t work, you’d likely want to call Sonos Support directly to discuss it.
When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.
Factory Resets are the cause of much grief, best avoid them if at all possible.
Even worth a call to Sonos Support before the Factory Reset as it wipes all the diagnostic data internal to the unit.
