My friend cant join me T5 zombie

[Gilmour_zer]

Hello, my friend cant join me in private match zombie, it work once every 3 days, We tried with hamachi, zero tier, I opened my port, I did everything the tuto on the forum said and it still doesnt work, few weeks ago it worked perfectly and now it doesnt work, someone know how to fix this ? thanks

[Polacco]

I have the same problem