Using your own router with the Motorola NVG510 - it absolutely works and it's easy to do!
Hello. I am writing this in an attempt to save other customers (and the AT&T staff) from many hours of work and frustration. I was a long-time DSL customer and had always used my own router behind the DSL modem. A simple setting on the modem turned it into a "dumb" pass-through and allowed my router to handle all the traffic as I pleased. Changing over to U-verse required a new modem and at first, that presented a huge problem with my router.
What took me about 7 hours of work, online chatting with multiple agents and even finally trying paid support with AT&T (and in both cases being told it's not possible to do), I succeeded in using my own home router with the NVG510 modem under the U-verse service. The process is fast and simple (in retrospect) and should take you about 10 minutes.