Xbox live on a netgear FVS318g problem.?

I have an absurdly complicated network set up. Changing it around is not an option. I am trying to get my xbox on this network to open nat instead of moderate. I am using a netgear FVS318g as my firewall. I thought I did port forwarding properly, it failed. I thought I did port triggering properly, it also failed. Any thoughts would be helpful!