Netgear MR314 - used to work - won't update now

I used to play MotoGP online... Rushed out and bought Ghost Recon today with
a colleague who just got Live, to find I can't update the dashboard

It won't let me play without updating, but won't update.

I tried both manual & automatic (DHCP). Xbox is connected directly to router
(straight cable, as always). I've tried mapping ports 53, 88 and 3074
through as I've seen mentioned, and even tried it as DMZ, just keep getting
"Xbox live is not responding. Please try again later"

Any ideas? I remember having problems signing up, but after that, playing
was fine... I can't find the max address (external interface) of the router
(if anyone can get it from my hostname (nevershutsup.com), let me know!), so
can't even try bypassing the router just to update (playing is usually fine,
and I can't leave router out too long, it's a server too)

Any suggestions welcome :o(
--
Daisy The Cow
Now playing: Nothing