im having a few problems, it will connect but not all the time and when it does it cuts off after a while. im using windows 7 tiny and t mobile broadband. when i test my connection on xbox it says - you can connect to xbox live but your current network configuration may limit your online experience. i press info and get this - your NAT type is strict. people on networks with this nat type may not be able to join certain games or hear other people while playing online. for the best online experience you need an open nat configuration. so any ideas? i dont know what a nat config is.
your problem is more than likely your tmobile connection. quite apart from the poor speed and latency of mobile broadband in general, the networks are often set up in odd ways and are very restrictive.