I tried to setup an Airport Express for wireless with AT&T DSL, had no luck using the logical process (see below) and couldn't find anything here, so here's what I did to make it work. The AT&T DSL modem I'm working with is a Motorola 3360 (has no wireless capability on its own, so I bought the Express to provide the wireless signal.) Logically, one would think that the 3360 should be set to bridge mode and the Express would be setup using the PPPOE option. That only resulted in the setup working temporarily, after a few minutes everything would stop working and the Extreme light would go to flashing yellow (something not right.) Also, no internet access. Error messages from the Express would indicate an IPv6 error, but experimenting with those settings would not fix the problem. I wound up calling Apple, and this is what the fix was: - Do not set the modem to bridge mode. Leave it in its standard default or factory setting. - Set the Extreme (under "Internet/Connect Using") to DHCP operation. You will get a "Double NAT error" message in Extreme, but it can be suppressed. According to the Apple rep, this is the correct and preferred mode for this application. - The Apple rep mentioned that apparently AT&T DSL uses DHCP, not PPPOE as might be expected, so this throws off a lot of people. Everything now works fine. I thought I'd post this here since I couldn't find it anywhere else and the standard Apple phone support only lasts for 90 days, so anyone past that time or buying a used unit might have to pay for this info from Apple.