For the last 3 years I've been with CenturyLink DSL, and had a deco m5 mesh connected to a C1100Z modem. Setup was quick and automatic. I have had almost no issues with it. 

Recently CL became Brightspeed. I was sent a newer modem. It's a C4000LZ. I had no problem getting the new modem set up and working, but I am unable to get my Deco m5 to connect and work with it.

I have tried deleting my old deco network, resetting the deco pucks, and have tried using each of the 3 pucks as the primary connection to the C4000LZ. Every time I try setting up a new network, I am unable to establish an internet connection. The primary deco goes from blue blinking light to solid red. I did sign in directly to my modem on my most recent attempt, and under device table, I am seeing nothing except for my laptop and phone. There seems to be no recognition of the Deco system by the C4000LZ wan/lan. My modem is setup as Dynamic IP, using IPv4. 

I am able to revert back to the old C1100 modem and get the deco m5's setup very quickly, so they still work just fine. The issue is in connection/communication with the new C4000LZ.

Please advise on next steps. TP-link support? Brightspeed support? What do I ask for? Other?

Thanks,

T