I did not have to do that with my AT&T DSL modem. The Speedstream 4100B DSL modem was configured to do the PPPoE on the modem. All I had to do was configure the router for automatic DHCP on the WAN/Internet port and everything worked fine so long as the router's local network IP address was not set to the 192.168.0.x range. If one wants the router to do the PPPoE login then they would have to configure the DSL modem into bridged mode, then set their router for PPPoE login and supply the login information. With ATT Uverse, the router they supplied me, when AT&T ported my area from DSL to Uverse, cannot be put into bridge mode. The option simply isn't included in the AT&T router firmware. I have to use their router. There are several ways to run my own router behind AT&T's but it takes some configuration of one or both routers to make that happen.