Offline and will not reconnect

My x40 complete has suddenly decided to go offline and will not reconnect. Nothing at all has changed on the router settings.
Any ideas, this is extremely frustrating.

It has now just reconnected and i think it was caused by confusion of the AI in the last task.  Basically a mop pad came off from an obstacle.  I put the moo pad back on and sent it home, which it did fine but then it didn’t clean again after that and i noticed it offline.  I set off the cleaning manually from the device and now about 15mins in it has cone back online.  I think generally the AI cannot cope with unexpected events and only some error free running time clears it.  I have seen something similar in the past.  I posted this in case it might help anyone in future.