Yea - I'm thinking there's something going on under the hood which is trying to prevent this or is unintentionally preventing it.
My routers are identical and I've verified there are no new firmware updates available for them. They're referred to as MI424WR Rev.F, but here's the more specific info from the System Monitoring page.
Firmware Version - 40.21.10.2
Model Name - MI424WR-GEN3I
Hardware Version - I
Physical Connection Type: Ethernet
Broadband Connection Type: DHCP
Broadband Connection Status: Connected
What's really frustrating is that everything else works! I can add devices to the LAN or Wireless side of the secondary router and they get IP's from the primary router DHCP server ... and everything is network reachable in both directions. Is an ideal LAN extension.
There's just something messing with the DHCP connection to the verizon network.
Get this ... I even tried "Disabling" the Coax interface on the "Network (Home/Office)" and it resulted in a breakage between the "Network (Home/Office)" primary and secondary router networks (as I expected), but I was hoping to also see that when I did this, it would stop the DHCP interferance with the WAN side of the primary router ... yet it still caused a disconnect.
Sounds like something outside of IP is going on that allows theses two routers to see each other and stop one another from co-existing. They must really want to sell those ECB2200 .... sigh ... that won't work for me because I'm doing all this to get a handful of RJ45 connections behind my TV and to extend my wireless coverage in the downstairs of my home and I don't want to install a separate MoCA bridge and an additional router to get the ports behind the TV - too much network management. I've got a "stick pc - MINIX" behind my TV with storage that I'd like to be able to FTP into ... and the more gear I throw in between all these things, the uglier it gets.
-Robert