Posts from Configuring the connection. Let's clarify all the details.

I bought a new router, and I can’t play through it. Today, both Maretti and GoD wrote to me at almost the same time with the same problem. Are there any of us who are knowledgeable about this and can create a good, universal manual, since it seems that many people are facing similar problems?

It might help – try launching the game through the .exe file, not through the launcher.

I have to run the Launcher by right-clicking and selecting "Run as administrator" for it to work {or add an exception}.

Access the router settings through your browser (the IP address for accessing the settings varies for each router model). In the settings, find the firewall and disable it; you can also open ports there if disabling the firewall doesn't help. To be absolutely sure that the issue is with the router, connect the internet cable directly to your computer. If everything works fine when connected directly, then the problem is definitely with the router.

There was already a thread about routers; someone wrote a solution to the problem there.
/topic/7076/

There was already a thread about routers; someone wrote about a solution to the problem.
/topic/7076/

I read it. The proposed solution there involves using a TV. I suggest we develop a universal algorithm for everyone. I am sure that this is possible; we just need to find a competent system administrator among us.

There was an issue with the Asus router – the heroes would only connect when the game was launched without the HD mod. The problem was resolved by disabling the "Enable UPnP" option in the router settings.

I had an issue with my Asus router – the heroes would only connect when the game was launched without the HD mod. It was resolved by disabling the "Enable UPnP" option in the router settings.

This helped me too, when I recently reset my router settings.

Indeed, disabling UPnP helps fix the connection error.
In an attempt to understand why something that should help with the connection actually hinders it, I searched the internet and found information from our English-speaking colleagues about a problem within the game itself; according to them, DirectPlay cannot interact correctly with UPnP. This is likely due to the age of the game, as UPnP wasn't even known when it was created.
In general, feel free to disable this function on your routers if you are experiencing connection problems in the game, especially if the ping in Hamachi works normally. However, it's worth remembering that for some other programs to work correctly in this case, you may need to manually forward ports.

Regarding port forwarding: Ports for Heroes of Might and Magic: 2300-2400, 28800-29100, 47624 For Heroes of Might and Magic Online: 2700 (not sure where this information comes from), also 12975 and 32976 are mentioned. If I'm not mistaken, this didn't help me, but disabling uPnP did. However, for Diablo 2, connecting via TCP/IP (I have a static IP) was helped by: 6112-6119, 4000 :D :D :D

Help, I can't play through the router. (Without the router, everything works, but disconnecting it every time is not an option.)
The ports are forwarded as follows:

And it used to work like this. What has changed? I upgraded from Windows 7 to 10. But I installed Windows 7 separately (although without updates) and it still doesn't work. The router's firmware has been updated. I checked with an older firmware version - the result is the same.
The firewall and antivirus are disabled. Ping in Hamachi is working.