BayArea TANK

My brother is on the other coast and we want to play Halo and Brute force
which support System Link. So I setup a VPN server for him to connect to, i
start up a halo game waiting for people to join and he fires up halo trying
to join but he can't see my game.

His setup is pretty basic
Laptop running windows Me
Xbox
DLink Router, the one listed as LIve compatible. Both devices plug into this
as does the cable modem.

He can surf the internet fine, play on live fine and connect to me via VPN
fine.

Now on my side, things are a whole lot more complicated.

First my xbox ties into a Netgear 802.11b wireless bridge which talks to
another one which plugs into my netgear switches.
I have numerous hard wired and wireless clients in the house, couple laptops
and desktops. All talk fine on the network and internet.
My server (windows 2000) is steup with RRAS and pluged into the switch
The switch goes to a Sonicwall Firewall and on the other side of the f.wall
is my cable modem.

I can play on live, talk on the internet and talk with other computers in my
network just fine.

So what am I missing? Why can't he see my Halo game?