... and setting the other up as a DMZ .
Do you mean there is a setting in the x-box to set it up as DMZ?
If you mean in the router then setting DMZ should nullify any port forward settings to another machine afaik.
Still, it works for you
Does the router in the OP's question forward ports to an IP address or to a MAC address/NIC card name?
If the former, can you set static LAN IP address in the x-box?
If the latter you should just be able to have forwarding rules for both x-boxes with no DMZ.
Both of these assume you can specify different ports in each x-box though. If you can't do that then I'm at a loss
edit: ok, been reading a bit, cant choose ports in x-boxes, looks like the fixes are very router/firmware specific. I still can't see how the DMZ fix works, but others have it working with just upnp on and x-boxes set to DHCP (not static). Also, no port forwarding, but maybe port triggering would help if the simple upnp doesnt work on your router
There are 10 kinds of people, those who understand binary and those who don't.
Edited by Myth (Wed 29-Jun-11 15:28:27)