It does not matter what you use really FSD or XexMenu. The important thing is if your actually getting the DHCP assigned IP address and if your getting a clear route to/from the xbox to the computer. Easier way to check is to startup freestyle dash then note down your IP address. Once you have your IP then type in the following command at the command prompt:
ping <IP of xbox360 you wrote down>
e.g. ping 192.168.1.100
If you have an IP address and you are able to ping then I will suggest checking your router config to make sure you have the traffic/port allowed.