VEIN Server Ports and How to Connect (Fixing Join Failures)
A VEIN dedicated server needs UDP 7777 open for game traffic and a Steam query port (UDP) so the server can be listed. If you host at home, both have to be allowed through the Windows firewall and forwarded on your router. If you rent a server, the host handles that and gives you an IP and port.
The query port is where sources disagree: the VEIN wiki's examples use 7778, while the config key GameServerQueryPort is commonly seen at 27015. The honest answer is that it is whatever you set, so this guide explains how to check which one your server actually uses. Details reflect the 0.02x builds; confirm against the current wiki if something changed.
- Game port: UDP 7777 (
-Port=7777). Query port: set with-QueryPort=orGameServerQueryPortinGame.ini; commonly 27015 or 7778. Forward the one your server really uses. - TCP 7777 is optional RCON on setups that enable it. An optional
HTTPPortAPI, if you turn it on, has no authentication and must not be exposed to the internet. - Players can use the in-game server browser, the direct connect box in current builds, or add
IP:PORTto Steam favorites. - Most failed joins are a patch mismatch, a blocked UDP port, or a wrong password. A server that is not listed is usually a query-port or firewall issue.
On this page
Default VEIN server ports
| Protocol | Port | Purpose | Where it is set |
|---|---|---|---|
| UDP | 7777 | Game traffic from players | -Port=7777 launch argument |
| UDP | 7778 or 27015 | Steam query port, used for the server browser and listing | -QueryPort= argument and GameServerQueryPort in Game.ini under [OnlineSubsystemSteam] |
| TCP | 7777 | Optional remote console (RCON), where your setup enables it | Setup dependent |
| TCP/UDP | 8080 (example) | Optional HTTP status API if you add HTTPPort to Game.ini | Game.ini |
The VEIN wiki lists UDP 7777 for game clients and UDP 7778 as the query port, with a second instance on the same machine using 7780 and 7781. Host references and a Steam community thread by a self-hoster instead forward 7777 and 27015, matching the GameServerQueryPort=27015 value those references report as the default. Both can be right on different builds or launch lines. The reliable method is to set it yourself and forward exactly that.
How to set the ports explicitly
Put the ports on the launch line so there is no guessing. This is the shape the wiki and host guides use:
VeinServer-Win64-Test.exe -log -port=7777 -QueryPort=27015 -MaxPlayers=16Linux installs use the VeinServer.sh script that wraps the Linux binary with the same arguments. Do not forget the = signs. If you run several instances on one machine, give each its own pair, for example 7777 and 7778 for the first and 7780 and 7781 for the second, as the wiki does.
If you bind to one address on a machine with several network interfaces, host docs mention a -multihome=<IP> argument and the BindAddr key in Game.ini.
Firewall and port forwarding for self-hosters
There are two layers. The machine's firewall must allow the ports in, and the router must forward them to the machine's local IP.
- Give the server a fixed local IP
Reserve an address for the machine in your router so the forward does not break when DHCP reassigns it.
- Open the ports on the server
Allow inbound UDP 7777 and your query port in the Windows firewall (or
firewalld/ufwon Linux). - Forward on the router
Forward UDP 7777 and the query port to that local IP. The wiki points to portforward.com for router-specific guides.
- Check from outside
Ask a friend on a different network to join, or test from a phone on mobile data. Testing from inside your own network proves very little.
A home connection behind carrier-grade NAT cannot be forwarded at all; that is a limit of the ISP, not VEIN. Hosted servers do not have this problem. The host gives you a public IP and port, so DDoS protection matters more once your IP is public. See DDoS protection for what is included.
How players connect
- Server browser: servers appear in the in-game list when
bPublicisTrueand the query port is reachable. The wiki notes the in-game list has a display limit, so a busy list may not show yours. - Direct connect: current builds (0.023 and later, per host docs) have a direct connect option in the browser where you enter the IP and port.
- Steam favorites: the wiki's recommended fallback is to add
IP:PORTto Steam's favorites list and join from the Favorites tab in game. - Hidden servers: with
bPublic=Falsethe server does not appear in the list. Players would need to connect by IP; one forum poster found joining a non-public server unclear, so test it before announcing it.
How to check that the ports are actually open
First confirm the server is listening, then confirm the world can reach it. On the server machine, list listening UDP sockets and look for your game and query ports:
netstat -ano -p udp | findstr :7777
ss -ulpn | grep 7777If the server is listening but outsiders cannot reach it, the problem is the firewall or router. Most online port checkers test TCP, so they say little about a UDP game port. A real test with a friend on another network, joining by IP and port, is more reliable. If a join works for you on the LAN but not for them, that points at the router forward or your ISP rather than the server.
VEIN server not showing up or players cannot join: fixes
| Symptom | Likely cause | What to try |
|---|---|---|
| Server not in the list | Query port blocked or bPublic=False | Open the query port for UDP, check bPublic, and join with direct connect or Steam favorites to test |
| Joins fail after a game update | Server and client builds differ | Update with SteamCMD (app_update 2131400) and restart the server |
| Password rejected | Case or characters | Passwords are case-sensitive; one host recommends letters, numbers, dashes and underscores only |
Linux log shows dlopen failure for steamclient.so | Missing Steam library link | Copy or link SteamCMD's linux64/steamclient.so to ~/.steam/sdk64/ |
| Windows log says the Steam dedicated server API failed to initialise | Permissions | Run the server as administrator |
| Server will not start on Windows | Missing runtimes | Install the Visual C++ redistributables and DirectX runtimes the wiki lists; first run may prompt for them and a reboot |
| Listed, but nobody can connect | Only the query port is open | Forward UDP 7777 as well |
One useful readiness check from host docs: wait until the log shows SDR RelayNetworkStatus: avail=OK before testing a join. Also remember the server needs at least 8 GB of RAM to start, per the wiki, so an undersized machine can look like a network problem when it is really failing to load.
Frequently asked questions
What ports does a VEIN server use?
UDP 7777 for game traffic and a UDP Steam query port. The VEIN wiki's examples use 7778 for the query port, while GameServerQueryPort is often seen as 27015. Forward whichever one your launch line or Game.ini actually sets.
Can I connect to a VEIN server by IP address?
Yes. Current builds have a direct connect option in the in-game browser, and the wiki also suggests adding IP:PORT to Steam favorites and joining from the Favorites tab. Use the game port, normally 7777.
Why can friends not see my VEIN server in the list?
The usual causes are a blocked or unforwarded query port, bPublic set to False, or the in-game list's display limit. Test with direct connect or Steam favorites using the IP and game port.
Do I need to port forward if I use a hosted VEIN server?
No. A hosted server already has a public IP and its ports set up. Port forwarding applies only when you run the server on your own network.