Mordorf wrote: Have you tried opening the relevant ports as described in the below link.
http://support.microsoft.com/kb/908874

Yes tried that and still no luck, i also tried putting one xbox through DMZ and still one gets disconnected, as my new router has not arrived yet Ive been trying alsorts of things,

the funny thing is, this set-up used to work, as my 2 sons reminded me, the only thing that has changed is my number 2 son got him self a brand new xbox 360, (which came last week) as his other one died about 1 month ago.