Linksys Wireless Router :: E3000 - Two XBoxes And 2 Open NAT?

I am at my wits end with cisco and linksys. I have had three different linksys routers over the years.I have a WRT160N, and now I think I made the mistake of buying cisco's latest product E3000. I thought by now their Upnp would be worked out for 180 dollars. But sadly no even their most expensive latest product doesn't do what I want. All I want is to hook up two xbox 360s and have open NAT which is what NAT is supposed to do. Still the NAT does not open up for both systems simultaneously which is absurd. I have a sb6120 for a modem. Both xboxes are hardwired to the router. Upnp should be enabled as this is part of the router.  Also its job should be able to handle the two xboxes properly with one ip address that is its sole purpose.

I've tried one in dmz the other with static ip with forwarded ports that equals one open one strict.I've tried upnp enabled alone that equals one open one moderate.I've tried everything else the plan and simple fact is that it should work with upnp on and the nat in the e3000 will take care of the allocation of renaming ports to the single external ip address. By definition.