Problems extending an Airport Express n network on Comcast

I am writing you about a potentially new outting of Comcast's recent "traffic management" that has been written about quite a bit in the past month.

This example involves the new Apple Airport Express 802.11n and it's use of the new "Extend My Network" feature in conjunction with an existing Airport Extreme.  The new "Extend My Network" (also known as ProxySTA) feature works in a similar way as WDS, but allows the AX to share its connection through its ethernet port to other WIRED computers.  You can read more about it here, under Express exclusives.

My unit is able to join the network, obtain an IP address and all status lights indicate that it is properly attached to my network, but the Internet is unreachable.  After more than 12 hours of research and trial-and-error I discovered these threads that demonstrate that I am not alone.

The one thing that we have in common? We are all Comcast users. All other contributers to the thread that have successfully implemented this feature have their networks configured identically but do not use Comcast as an Internet provider.

It would seem to me that this is likely yet another attempt by Comcast to limit bandwidth usage and manage their traffic.

Anyone else feeling John's pain?