Problems with an XBox360

I have a client who’s XBox360 is misbehaving.

As far as I know, I’ve done everything right, but this thing can’t connect to the XBox service and keeps on coming back with an error message port 3074 is blocked.

Here’s the layout.
xbox.jpg
The traffic provider say they don’t shape or block any ports.

Starting at the XBox, it connects to an omni on the RB532 / R52. I’ve made a static IP in DHCP, so each time it connects, it’ll receive IP address 192.168.64.157/29
The RB532 connects to an RB600 based repeater via a R5H.

The repeater connects to a large AP that’s based on an x86 system with a number of wireless cards.
http://bigbertha.cape-connect.com/Gallery/IMG_1052.JPG

The AP connects to a RB450G that has several modems connected to it.

I mapped TCP and UDP ports as per XBox instructions, but I’ve still got this stupid “please check your firewall blah die bloody blah” error message on the XBox.

All ports are open on all the routers.

Does anyone have any idea as to the tricks to get an XBox to talk to the internet.

PS3 is so simple. Plug it in and it just works.

Thanks