Restricted NAT/not opened NAT for my Xbox360 using O2 Box2!!

I have been using my O2 Wireless Box2, i.e. TG585 V7, with my son's Xbox360 for sometimes without any problems. But about a week ago, during which time we had a "power glitch" from the mains lasting for only 1sec or so but still manged to mess up my Central Heating Controller, which I had to rest it to restore its normal operation. Then, according to my son, he started having this "restricted NAT or not open NAT" warnings whenever he wanted to play Xbox Live multiplayers games such as Call of Duty, Black Op. or even Hal Reach on line! My son's Xbox360 is being connected to my O2 Wireless Box 2 through one of its ethernet ports, not wireless. I have done:
a) restting my O2 Box2 to restore its system defaults but still has this issues.
b) logged in to the O2 Box2 as "SuperUser" and assigned the O2 ADSL's public IP Address (WAN address I believed) to this Xbox360's user through DMZ but it still gives me the same issues after rebooting. Noted that my nPnP is still enabled though.

Therefore UNLESS the O2 Wireless Box 2 is partly FAULTY, which I do not know as I don't have other equivalent Modem/router to test it. I'm on O2 Standard ADSL2+ (LLU instead of the ADSL Max). Do I need a NEW Modem/Router to replace the O2 Box2 in order to test this "restricted NAT" setting or I haven't done SOMETHINGS else in the O2 Box which may resolve this situations??
Thanks for any advices that I might have missed!!

P.S: My O2 Wireless Box2 is using 7.4.20.5 FW and is operating O.K in other aspects.

Have you tried assigning your 360 a static IP address then putting that static IP address in the DMZ box area of your router?

Another thing to try is to disable UPNP (combined with the above) if it doesn't work

It could be possible the power threw the routers routing out, you might want to just try unplugging it and letting it sit for a bit.

Thank you for replying!! I did try copying my Xbox360's address to the DMZ box and hence gave my Xbox360 a "public IP address" instead of through the NAT in my router, but it did not work either. However it occurred to me that it was my xbox360's network setting was some how corrupted, i.e by the previous Power-Surge event I had encounted, and resulted into my Xbox360 network IP was restricted. I just restored my Xbox360 network setting to "Factory Default" and my resultant Xbox360's NAT is now "opened". Problem solved.
Thank you for your suggestion.

It's worth ensuring you have the latest firmware for the O2 Box

http://www.o2help.co.uk/router-upgrade-firmware/

Edited by nredwood (Sat 26-Feb-11 17:32:58)

Thank you for the O2 FW update info.!