The AT&T router I have has an "IP Passthrough" mode which basically does a DMZ with my downstream router, but the router receives a public IP address. The AT&T router is essentially "invisible", but it takes up so much physical space, power, costs me $10/month, and is one more link in the fragile chain between me and the Internet.

Other comments here mention how to put the AT&T router behind a Ubiquiti gateway and proxy the authentication to it via some scripts. This reduces the reliance on the AT&T router for direct traffic, but you still need the router operational for those authentication handshakes.