Xbox Live Clans

hi had another issue. im having trouble getting an open nat. ive tried almost everything. I have a desktop computer in the living room connected to a speedstream 4200. THen i have that connected toa dlink 524 forwireless access. In my room i ahve my laptop brdiged to the wireless conection and my laptop connected to my xbox. I can get on xbox live but i have an strict nat. ive tried almost everything from upnp, to dmz to port forwarding. because i have two routers should i do something different? iehar something like pppoe maybe? not sure i need some help after countless hours trying to figure this out thankyou.