We've been playing PZ previously a long time and also used the dedicated server on my machine (Win 7, batch-file as steam-variant).
Everything was working fine, friends were able to connect by ip-address, everything went very smooth.
A few weeks (or months?) later we are back at PZ and I wanted to make a server again, this time outside my own home (hosting server, Ubuntu).
But we weren't able to make a successful connection between any client and the server.
At first it was the firewall, of course.
Then there was a difficulty with the ip-address, because the server has 2 of them and there is no option to tell the game, which one to use (or at least I can't find any).
But now, all those problems are out of the way and still it's not possible to connect.
To be more precise:
The clients are getting the error, that's not possible to make a p2p-connection.
Looking on the server via netstat, I can see everyone trying to connect, and I also see the reason, why the server is unable to send a reply, but I can't get the source and solution for this.
As said when I'm looking via netstat for those incoming connections by the client, I can see that the client is sending the internal lan-ip instead of the public one.
Of course, the server, residing in the internet, is unable to reply to any internal ips and so the message pops up, that's not possible to make a p2p-connection.
When starting the client in the non-steam-variant (by using the parameter -nosteam), but letting the server be as before, it's not even getting this far and only telling "server does not respond".
Running both, server and client with "-nosteam" it works just fine!
But I guess it should also work without those launch parameters, also as the client is telling, that it should be possible to connecto to a non-steam server with a steam-client
As multiple users have the same problem and showing the same characteristics when trying to connect, we can tell that it's not a problem on the local lan site or everyones routersettings.
Any ideas how to fix this?