Also, you can add patch "Enable Proxy Support" to EXE. In this case, EXE will ignore IPs from network packets for char & map servers.
If it will not help, your friends should download "connect_log .mix" and copy it to the game folder. It will create "connect_log.txt".
https://mega.nz/#!lI90TTxI!6l2xp20o9gdDrpsKBohMaR46PZqMtHosYSWLlK5kO88