I have a collection of TP Link Deco devices in my wireless Mesh network. X60 as the main unit, a couple more X60's an X20, 3 P9' and an M4.

About 2 weeks ago, performance seemed to be deteriorating so I investigated and found that in the Deco app , all but the main unit are showing as offline. This can't be the case, as I have things connected via Ethernet cables to many of the devices and they are working. 

I have, of course, turned off and on many times, attempted to update firmware over the air. Nothing appears to help. 
Has anyone experienced anything like this, and does anyone recommend anything other than reconfiguring the mesh network from scratch?