Why can't i join my friends halo2 game or matchmaking?

it says i have network problems. Also i cant even play matchmaking games, it backs out before it starts

Why can't i join my friends halo2 game or matchmaking?
If it won't let you sign in to your gamertag then goto troubleshooting if it is an IP address problem then unhook the power cord from your modem (If modem has a battery unhook the ethernet cord) and turn your system off for 3 min and plug it back in wait a few more minutes then try to sign in.





If it is a DNS problem unhook the power to your router and plug it back in and wait a few





If it is a cord problem check all of your cords





If all three come up in the trouble shooter as fine then the 4th one will say nothing is wrong and then sign you in.
Reply:There's only a few things I know





1. Fix the connection, or look at it, see if it's functioning correctly.





2. Make sure you downloaded all of the maps already.





3. His connection have problems?





I don't know, it's mostly #1