Check to see if your nat type is open. If it is not i would recommend to call your internet provider and have them walk you thru how to set it it open. If you dont want to do that google might have the answer for you if you understand that lingo.
Is your ISP Virgin? I remember there is a setting needed, hopefully someone can remember and post it.
Also try going into settings on the console and go into power and startup. In there change it from instant on to energy saving mode, back out and turn console off. Restart and try again.