My Sonos One SL had been set up for 9 months and worked perfectly. Yesterday i went to use it and it was not on the menu for available rooms. I tried a hard reset and then to add it back to the network. It can be located and then the app tries to connect to the home wifi network it comes up with this message: “Your Sonos One SL has been added but may not appear in the system tab. If so, unplug the power cord and plug it back in to finish set up from the system tab”. Once done it still does not appear on the system tab

I have tried to add it back to the network by hard wiring it to the router but this also failed. 

Thanks for any advice given.