Is it pulling a "live" internet IP address?
In EvoX go to "Network" and see what the IP address is. It should be grabbing an internal IP address.
192.168.1.xxx
Make sure the computer you are using, and the Xbox have both pulled an internal IP.
I had weird problems with my Xbox pulling a live IP from my ISP when I was connected to the net. (Through my Linksys router/gateway) I shut everything down, disconnected from the net, and restarted. Made sure all devices pulled an internal IP.