Technical issues and problems with WoGa.

Hello everyone on the forum. I really need your help. I have two computers, and both have the same version of the game installed. We want to play over the network. We first configured Hamachi, then OpenVPN. An IP address is assigned. We changed the priority in the network connections so that the correct IP address is displayed in the game. Both computers have Windows SP3. I create a game, my friend sees it, but he can't join. It gives an error, a connection failure. We've tried everything, but nothing works. What could be the problem? What services might need to be enabled/disabled, how should it be configured, maybe some ports need to be set up? The modems are DLS 2540u and DLS 500T. I've searched the entire internet, but I can't solve this problem. By the way, my modem has 4 ports, and I tried connecting 2 computers. The same thing happens. Then I disconnected the phone cable so that there was no internet access, and everything worked. But the problem is that the two computers are located at a great distance. Thank you in advance for your help.