Hi!
Multiple people were able to connect by unblocking the port or using Hamachi. Therefore, it's definitely possible.
Could you please try connecting to your friend again, wait for about 15 seconds, then exit the game and send me the file located at the path using https://pastebin.com/
Path: C:\Users\YOUR_USER_NAME_HERE\AppData\LocalLow\CHERNOZEM\CHERNOZEM\Player.txt