Players Can't Join Your SCP Secret Laboratory Server? Fixes

When players cannot join an SCP: Secret Laboratory server, check these in order: the server's UDP port (7777 by default) is open, the server is on the same game version as the players (run buildinfo in LocalAdmin and update with SteamCMD app 996560 if it is behind), the whitelist is not switched on by accident, and you edited the config folder that matches the server's port. If the server crashes or kicks people right after a game update, EXILED or LabAPI plugins that have not caught up with the new version are the usual cause.

Note that a new server not appearing in the in game list is a different problem. Servers only show in the public list after Northwood verifies them, so until then players use Direct Connect. This page is about players who try to join and fail.

Step 1: Join with Direct Connect yourself

Before changing anything, test the address the way your players do:

1. Launch the game and click Play.
2. Click Direct Connect.
3. Enter the server's public IP and port, such as 203.0.113.10:7777.

From inside your own home network, use the server's local IP instead, because many routers do not handle connecting to your own public address from the inside. If even the local IP fails, the server itself is the problem, not your network.

Step 2: Open the port

SCP:SL uses one UDP port per server, chosen when you start LocalAdmin (7777 unless you picked another). Forward it as UDP on your router to the server machine, and allow it through the firewall. Every extra server on the same machine needs its own port.

If the forward looks right and still nothing gets through, your provider may be using carrier grade NAT. See how to tell if you are behind CGNAT. Our port forwarding guide covers the router steps.

Step 3: Match the game version

SCP:SL updates regularly, and players get the new client from Steam immediately. A server one version behind refuses them. Check what the server runs by typing buildinfo in the LocalAdmin console, then update:

steamcmd +force_install_dir C:\servers\scpsl +login anonymous +app_update 996560 validate +quit

Northwood's update guide adds a trick for when a server stubbornly stays old: use app_update 996560 -beta public validate instead. If you installed through the Steam dedicated server tool, check that Properties, Betas is set to none.

The reverse also happens. If you put the server on a public beta branch for testing, only players who opted into that beta can join it. Switch the server back to the normal branch when testing ends.

Step 4: Check the whitelist and slots

A whitelist left on from an event refuses everyone not on the list. In the server's config folder, open config_gameplay.txt and check:

enable_whitelist: false

Also check max_players in the same file. A full server turns people away, and reserved slots only help players listed in UserIDReservedSlots.txt. Our guide on whitelisting an SCP:SL server covers both files.

Step 5: Edit the right config folder

SCP:SL keeps configs per port, in a folder named after it:

If your server runs on 7778 and you edit the 7777 folder, none of your changes apply. That includes passwords, the whitelist and player limits, which makes the server behave in ways that seem impossible. Check the port LocalAdmin started with and edit that folder.

Step 6: Plugins after an update

If joins started failing right after a game update, and the server runs EXILED or LabAPI plugins, the plugins are the prime suspect. Big updates often break them until their authors release new builds. Symptoms are crashes on start, errors in the console when a player connects, or rounds that never begin.

To confirm, move the plugin files out of the plugins folder (keep a copy) and restart. If players can join, add plugins back one at a time. Then wait for updated builds, or roll back the server to a backup taken before the update. Our EXILED plugin guide covers the folder layout.

Step 7: Read the LocalAdmin console

LocalAdmin prints each connection attempt. If a player is rejected, the console line usually says why: a ban, the whitelist, a full server or a version difference. Ask the player for the exact time they tried, then read the lines around it.

Quick reference

On a hosted server

On a GamezServers SCP: Secret Laboratory server, the port is open on a fixed address with DDoS protection, Auto Update pulls new builds on restart, and the live console shows LocalAdmin's output, so most of this page comes down to Steps 4 to 6. The port named config folder is in the file manager, and a one click backup before each game update means a plugin that breaks can be rolled back in minutes. Getting listed publicly still needs Northwood's verification, which our SCP:SL hosting guide walks through.

FAQ

What port does an SCP:SL server use?

UDP 7777 by default. Each server on the same machine needs its own port, and configs live in a folder named after it.

How do I check my SCP:SL server version?

Type buildinfo in the LocalAdmin console and compare it with the current game version.

Why can players join by Direct Connect but not find my server?

The public list only shows servers verified by Northwood. Until then, Direct Connect is the way in.

Why did my server stop working after a game update?

Either the server has not updated yet, or EXILED and LabAPI plugins need new builds. Update the server, then test without plugins.