Private match with friends
This guide will teach you how to play with friends over the internet in a private match.
Note this guide requires you to know how to port forward. If you do not know how to do this please consult your internet service providers' documentation/support. Every router is different so there is no one way I can explain on this guide on how to do so.
The host of the game needs to port forward port 27016 with the protocol UDP, this will enable friends to connect. (27016 is MW3's default port)
You can double-check the port is correct by typing
net_portinto your console in-game and checking it's value.
The host of the private match needs to navigate to 'Private Match' from the main menu and setup the game as they wish, once happy with the setup they need to start the game via the 'Start Game' button.
The host of the game now needs to provide their public IP address to everyone who wishes to join. To learn what your public IP address is simply visit this site: https://whatismyipaddress.com/ (You need the ipv4 one)
All friends now must from the main menu, go to 'Private Match' then open the console with the tilde key and then enter the following command using the IP the host provided:
connect HostsIPAddress:27016(Note the port can be omitted if default port)
This completes the guide, your friends should now have connected to the private match!
If you and some / all of your friends are on the same LAN they connect through the internal IP, if all players are on the same LAN portforwarding is not necessary.
If you really can't portforward use rAdmin VPN as Hamachi won't work in most of the cases.