1. The ISP blocks the connection.
2. The users that are attempting to share have a firewall up.
2a. In the PC.
2b. In the router.
3. The router is not able to auto configure for a game server. I will not write how to fix that. You hit the game's forum for that one. For LoL they have forums all about their game, servers and mroe and I'd be duplicating that issue here but it's usually item 2 followed by 1.
I got a friend who lives like 5 minutes from me. We play a lot of games, BUT, we can only connect to a game server and play together if someone else host
Basically, here's an exaple:
• I can play league of legends with him, because the game provides a dedicated server;
• Minecraft: we can play together IF someone else hosts, because if he's the host, I can't connect to the server, and same applies if I'm the host;
• CoD MW2 has multiplayer games with local hosts, that means that a player is hosting, we can connect to a game, but if the host leaves and one of us become the new host, the other gets disconnected. Also in MW2, we cannot play spec ops because he can't connect. (it's 2 player only)
• Games like Civilization, age of empires and blabla that I host he can't join
Every game is bought on steam, not cracked. We both got open NAT. We both tried to disable windows firewall, router firewall and antivirus. I literally bought a whole new pc, and the problem persists.
Any idea on how to fix this problem?