I have the Main Deco connected to the modem.  It is solid green and working well.

Wifi signal has been disabled on the modem.  DMZ+ set up on the modem.  

I have 5 other sub Decos in the house on three different floors.  They all will go online green for a while (day 1) and then flash red.  All of them flashing red, disconnected after a day or so.

Here's what I've tried: 

I factory reset everything, delte the network, and start over.

I have rebooted and restarted everything 1000x.

I have tried different ethernet cables, different ports on the modem.

I have brought satellite units (almost all of them) to test functionality right next to Main Deco.  No dice.

If the Main Deco is working 100% of the time, and initially the sub-units are working (when I start over fresh) and then they all start blinking red...what could be happening?  All disconnected.  I am suspecting it's some issue with the setup of my Modem.  AT&T Pace 5268AC.  It makes no sense to me.  I'm about to jump off a roof, I can't spend another day on trying to fix this but I don't want to return it and start over with another one.

I contacted customer service/support, was on for an hour plus, the lady could not figure out what was going on and elevated my request.  She said someone would contact me.  It's been 4 days and no contact.