How to open ports for Xbox Live?

i have an xbox 360 s console and i want to connect to xbox live. i have an eircom modem and a compaq computer. i want to know how to open port 3074 for xbox live. i have already opened everything to do with xbox and xbox live!

Any help appreciated!How to open ports for Xbox Live?
Ive tried this many times with many routers and its not worked (for me) but you have to change the port setting on the router. this changes dependant on router. may i suggest looking for a guide online specific to your router.

Hopefully this will help. im at collage atm and dont have time 2 look for a guide for you.

Good luck