Let me explain the situation. I currently have Windows Vista 64-bit, and the game runs perfectly. Until recently, before I installed a router, it could normally detect my IP address, and I could play online. Everything was great, and I was found without any problems (except for the times when the firewall blocked it). Now, with the router, it gives me the computer's address within the local network, meaning the address assigned by the router, and, of course, I can't be seen because the IP address is different and, moreover, it's a local one. Something similar happened with eMule because it also reacts very positively to having a static IP address, and without it, it can't connect to the largest servers due to Low ID. However, after reading about this, I was directed to a website that explained which ports to specify in the Virtual Server in the router's admin panel. Therefore, I think the problem here is similar. Knowing the ports, I'll enter them, and everything will work.

P.S.: I tried Hamachi, but I wasn't impressed. Then I figured out the IP address issue, and everything became normal.
P.P.S.: Hamachi will be useless on Vista; it won't work