[Multiplayer][Server] Connection issue: failed to establish p2p connection with server.

[Silltop]

Hello,

I'm hosting my own PZ server on virtual machine.

I'm getting error on client: Failed to stablish connection with server.

Error on server: OnP2PSessionConnectFail

First i was suspecting that the issue is caused by mods, so I removed them, still got error.

Server has firewall that is blocking everything, except the ports that are mentioned in documentation.

So I started to monitor network traffic using Wireshark.

It turns out that Project Zomboid is using classic-stun protocol?, and server is communicating with client using whole range of random udp ports from like 35000 to 61000. Output from ss command:

udp UNCONN 0 0 myip:51425 0.0.0.0:* users:(("ProjectZomboid6",pid=4748,fd=62))

udp UNCONN 0 0 myip:35629 0.0.0.0:* users:(("ProjectZomboid6",pid=4748,fd=55))

udp UNCONN 0 0 0.0.0.0:35947 0.0.0.0:* users:(("ProjectZomboid6",pid=4748,fd=57))

My question is, what port range is used for client-server data exchange?

I opened ports 35000:61000 and I was able to connect but I still need to know correct range of ports that should be used.

Seems like it's a common issue for hosts, maybe ports for this protocol are not specified at all?

[Silltop]

Problem is possibly related with steam ports for p2p connection. 

If you add -nosteam option on both server and client you do not have to open this range of ports only port 1626 udp is required.