I cant connect to xbox live from not being able to download the update?

I got a new modem and have changed MTU setting and NAT settings but nothing has worked. It has occured to me that when i test connection between the internet and xbox live it stops and says an update is required. When i click on update it never downloads, the bar just stays at zero. So is it the update that is stopping from going on to xbox live and if so how do i get the update to work?