Indeed -spot on.
It needs to be able to call back to DirecTV's servers to make sure you still have active DirecTV service, that the Nomad is on the same account as the receivers it sees, check that your devices are registered, etc.
The router needs to allow nomad to "call out" on the Internet for User Account Authentication. That typically means no firewall or setting should block nomad from that communication.
Some folks use a DMZ setup to accomplish this - puts the device outside of your normal firewall, which is OK on known hardware and communications like nomad.
In my case, the router setup allowed for the pass-through of the IP to the Internet.
Hang in there..it sounds like you're really close to getting this done.