NAT Punchthrough attempt from target failed

So, i have almost everything working.

When i click on connect at my server it shows me IP and everything but then after a second it shows:

And then nothing happens, in the master server it shows me that i have disconnected again…

The server admin and me have checked everything, ports etc are open, settings are right but we cannot get the NAT…

Why is this?

I hope that someone can help me! Thanks!!

Someone having this problem too? Literally i have checked out every single post from people having this error, but i cant figure out why this is happening