First of all let me thank everyone that might reply to my query.

I  have an M4R mesh system. It has worked pretty much flawlessly for more than 3 years. However, recently it has become a real pain.

The following is the layout of my network.

Comcast / Xfinity gateway (it is not a Arris router but a piece of SCHIFF that Xfinity now sells)

Mesh:

Unit 1: Main unit is running is V2 running FW 1.6.1 (this unit was originally configured as a router with the gateway being 10..0.01 and the Main being 1.0.0.2) It is now an access point and is located in the Master Bedroom.

Unit 2: Bedroo (located in the hall just down from the Main Bedroom) is running V2 FW 1.6.1.

Unit 3: Computer Room (this unit is just the other side of the funace that is located between the hall bedroom) it is running V2 FW 1.6.1.

Unit 4 Studio ( again all thise  units are litterally in a straight line) running V2 FW 2.5.4

All of this, as I said, was running completely flawless until recently. Now the studio goes off line. No matter what I do, when the deco is in the Studio it will not cnnect to the main.

I have removed the unit from the mesh and then rejoined it. I have changed the Main from Router to Access Point. Nothing works. I am about to ditch this hardware and get something more modern but can't help but think that I am misssig something.

BTW, I have reset the Main Unit and joined all the satellites and that did't work either. I am at a loss to understand why a system that worked for 3 years all of the sudden stopped.