'Let's play Heroes 5 online.'

Help me, kind people! My friend and I have the same version of the game and the same version of Hamachi, but when connecting to the network, instead of a green star in the menu, a blue arrow appears, and it says "relayed (slow)." The game runs very slowly for the first ten minutes, and then it crashes back to Windows. We disabled all antivirus programs, firewalls, and other unnecessary software, and also tried different versions of Hamachi, but nothing works. Our internet connection is good, 100 Mbps. Thank you in advance.