Network Problems w/xbox

[Christiaan Knol]

Hi,

Having recently been given an xbox I have tried to connect to the 
"Live" service so I can play against a friend, however no matter what I 
do I can't seem to get it working.  Here's what I've tried:

- Alcatel Speedtouch Pro ADSL Modem (with relevant ports opened up)
IP: 10.0.0.138

- Airport Extreme Base Station
IP: 10.0.0.10
Subnet: 255.0.0.0
Router: 10.0.0.138
DNS: 203.0.178.191 (as supplied by ISP)
Sharing out IP's in the range: 10.0.0.1 - 10.0.0.5

- Powerbook 10.3.4 (via Airport Extreme)
IP: 10.0.0.1
Subnet: 255.0.0.0
Router: 10.0.0.138
DNS: 203.0.178.191 (as supplied by ISP)

This has been working fine for internet access. So I thought I could 
turn on 'Internet sharing' and share the wireless connection via 
ethernet to the xbox. This is where I'm having trouble. What I have 
tried on the xbox:

- xBox:
IP: 192.168.2.2 (ifconfig tells me PBook is 192.168.2.1)
Subnet: 255.255.0.0 (also tried 255.0.0.0)
Gateway: 10.0.0.138 (also tried 10.0.0.10 and PBook IP).


I have tried searching the net etc but am still none the wiser.  Any 
suggestions?  Can anyone see why this won't work?  I have thought about 
getting an Airport Express to hook the xbox up to but have read mixed 
reports whether that would work too...

Thanks,

Christiaan