Mw2 private server help

Well whenever im hosting a game in private server a lot of people that try to join get unable to connect to host. What can i do so people can join my games?
what should i change? and i heard it was a router problem i have linksys router. hope you can help.

thanks

You need to change your NAT to open.
You can do that by googleing/search on MPGH or aIW about port forwarding.

after i do it and i do public matches will people be able to join my games also?

Yes, open NAT = You can host.