You are making us, shoot into the dark.
It would help to know at least..
What is the brand and model of your router?
If you are the original poster (OP) and your issue is solved, please remember to click the "Solution?" button so that others can more easily find it. If anyone has been helpful to you, please show your appreciation by clicking the "Kudos" button.
I am having the same issue when I play call of duty blacks ops my NAT type is moderate which limits me to play with friends, my router is a 7500 westall router all firmware updates are complete have had this router for about two weeks and I don't lag but do get kicked from games because of my NAT type. I have tried many different solutions like enabling UnCp settings I like if I remember that's what its called. I would like step by step instructions for changing NAT type have spent about 5 hours trying but got know where.