XBOX 360 System Link question

[Shuzzilay]

So my roommate and I are trying to system link Red Dead Redemption with a crossover cable. We both have the same game version, etc. I have the older, original xbox 360 with a wireless USB adapter and he has the newer "Slim" edition. System link requires both of our systems wired and connected (to XBOX live), however when I plug my cable in to my xbox it immediately drops my wireless connection in favor of the wired one (despite the fact that it runs directly to my friend's xbox). And, when it drops my connection, I lose connection and am unable to join. Is this an XBOX compatibility issue? His xbox works fine connected with both wirelessly to our network, and hardlined to my system.

EDIT: I am connecting both systems, THEN booting them both up.

 

[getochkn]

I'm pretty sure only 1 connection can be active at a time. So both systems would need to be connected to a router and the net and each other.

 

[Shuzzilay]

I'm pretty sure only 1 connection can be active at a time. So both systems would need to be connected to a router and the net and each other.

But how would you connect to both a router/net and another xbox if there can only be 1 connection active?