Xbox 360 Slim not connecting to internet

My Xbox 360 Slim has never connected to my internet, I want to fix it. when I go to the network setup, it connects to the Wi-Fi router, but fails to connect to the internet in the second step. I have tried wireless and wired, same think, I have tried all the fixes available, none worked. I want to get this fixed finally. and help would be really appreciated

:)