Required files and settings for playing Heroes 4 in multiplayer.

Hello everyone.
Nostalgia hit me, and an opponent appeared – we decided to play online. However, nothing works. Specifically, creating a game fails.
When attempting to create a game over the network, it says “failed to open DirectPlay when opening the connection” or “host enumeration error. You should install the appropriate protocol.”
Windows XP. I have a network through a DIR-300 router.
Heroes of Might and Magic(tm) IV The Coming Storm. From Buka, but without the disc.

Please help me figure this out.