I have a network of three Deco M5 devices, all connected over the ethernet network in the house.  Recently I noticed that the one in the office can't be found by the Deco app (Android).  It just shows the message "We couldn't find the Deco".

The light on the affected unit is steady green.  I've tried power cycling that unit, rebooting the whole mesh, changing the ethernet socket on the device but can't get any life out of it.  Do I have to assume that it is now dead?