I'm trying to set up SmoothWall like the following:

AT&T UVerse modem/router --->SmoothWall box ---> AT&T 2Wire modem/router ---> wired/wireless Devices.

1. I've installed SmoothWall on a box with two NICs.
2. Configured it following these steps: http://www.youtube.com/watch?v=2w28gn5nDlM
3. Connected Red to Uverse and Green to 2wire, and no go. SW is not pushing the connection through to 2Wire.

Is there any configuration that needs to be done to the 2Wire for it work?