Router MTU settings for Xbox Live

Ok this is driving me nuts. I use this model router – Netgear WNR834bv2 and for years it has been fine connecting to Xbox Live and today it tells me my MTU settings are not high enough. I have not touched the settings for months which means this is impossible becuase its; basically telling me that the router cannot handle an Xbox Live connect which is basically bollocks. Any ideas?
Answer #1
reset the router maybe usually is a reset button on the back of the router, also have you opened up all the ports so xbox live can run the best?
Answer #2
I have one of those routers, really reliable.
Have you updated the firmware ?
I don’t use Xbox Live, but perhaps it is a firmware issue ?
http://support.netgear.com/app/answers/detail/a_id/1123