TexasCHLforum.com

let me try to translate what the ATT people said

ATT: You have to use our router
ATT: That wont work

What they meant is that all they understand and support.

In the past people used to stick with the ISP provided solution because the ISP would help support it - Now as Charles has seen they pass you to "advanced " support which is paid 3rd party support. And because the 3rd party is referred by the ISP they often share the same Service level agreements and the same Limits - which means they wont offer any good other solutions for interesting issues because they cant. Most routers provided by most ISPs can be put in "bridge " mode so that DHCP and other features are turned off and in some cases they pass the external IP over to the router of your choice.

ATT and Fios both have installs that might require the Moca part ( coax ) of the router to be used - but at least in the case of Verizon you can just get a moca bridge to provide IPs to your Set Top Boxes ...

Even if you cant get the ISPs router in bridge mode you can still install a second router behind it and set the 2nd up with a different IP range. That MIGHT break some work VPN connections but most networking devices and VPNs have become more tolerant of nested networks in the past few years ...