Friend can't connect to server but another one can

[Cupcaick]

Good evening,

As of late we are having a little issue.

One of my friends which I have been playing Factorio with for some time has no problem joining my server, and I don't have any issue joining his. he can just come on and play. But another one of my friends, who just recently bought the game, can't connect to my server and I can't connect to his.

We can however connect to public games without any issue.

Does anyone know what the issue might be?

Thanks in advance,

Cupcaick

[IIPoliII]

To connect you he could need to open the udp port of factorio.
You can found it here https://wiki.factorio.com/index.php?title=Multiplayer

I don't know if this could help but try

Poli

[AlienX]

Just need some more information for this.
You say that this player is able to connect to other multiplayer games, so this tells me that his outgoing factorio ports are not blocked (as per Poli's suggestion)

Is your server hosted at home, or is it hosted by a Game Server Provider?
If it's the latter, can this other player ping the IP Address of your server?

try performing a traceroute from him to you.