Help Please!! Cant Connect to Friends Online

Hi people i have a problem. For some reason i can not connect to my friends when they invite into their party on Call of Duty World at War. There is only like 1 or 2 friends that i can directly connect too. I dont know if its my new router which is a ****** N router because after i installed it it said somthing about not supporting ip fragement to some games. I dont know if thats it or what. Please any help would be apprecitated. Thank you

Something you could try is putting your PS3 into a DMZ or demiliterized zone. It will basically just opens up all internet traffic to your PS3.

PSN: Zizaner