Technical issues with Heroes III.

Guys, help me solve a problem with Heroes of Might and Magic III: The Shadow of Death, version 3.0. Recently, when I try to enter the multiplayer mode and go to the TCP/IP tab, the game freezes... I can't play online, even though it used to work fine. I've already reinstalled the game and enabled compatibility mode with Windows XP, but it didn't help... What's the problem? Maybe someone can help?