There seems to be a bug in the way EvoX v+3921 handles the networking or something.
I was having a lot of problems with dvd2xbox not working properly, and I just discovered that if I boot into EvoX without my LAN cable plugged in, then dvd2xbox works fine. No matter what changes I made to the dvd2xbox config, it just wouldn't work if I launched it from EvoX with the LAN cable plugged in.
I then tried using Avalaunch as my dashboard, and running dvd2xbox from there. It works without a problem, with or without the LAN cable plugged in.