Fougerite

But in server console, I can see my connection (and immediate disconnect), all 3 ports are opened, I even try to completely disable Windows firewall, but still getting this error. Could you please help me? Thanks in advance!

Are you launching your client as an admin?

Yes.

I asked my friend and he has same issue.

Any idea?

What are you typing to connect to the server?

net.connect iport

But what is the ip and the port lmao..

net.connect rust.ceskejparan.cz:21111

And you set the server's port to 21111? If the query port is 21112 and 21113 the client cant connect since they are definetely closed.