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Overview

Nitrox Unlocked allows you to host dedicated servers for Subnautica multiplayer. You can run servers using the launcher interface or via command line for headless operation.

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System Requirements

Minimum Requirements

  • Subnautica installation
  • .NET 8.0 Runtime or higher
  • Available UDP port (default: 11000)
  • 2GB RAM minimum

Recommended

  • 4GB RAM for better performance
  • SSD for faster world loading
  • Stable internet connection
  • Port forwarding capability

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Starting the Server

1

Open Nitrox Launcher

Launch the Nitrox Launcher application.
2

Navigate to Server Management

Click on the “Servers” or “Manage Server” tab.
3

Create or Select a Server

Either create a new world save or select an existing one.
4

Start the Server

Click the “Start Server” button. The server will:
  • Initialize dependencies
  • Load game files from your Subnautica installation
  • Bind to the configured port (default 11000 UDP)
  • Load the world save
When using the launcher with IsEmbedded mode enabled (default), the server runs within the launcher UI rather than opening a separate window.

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Command Line Server

For advanced users and headless server hosting: 
# Navigate to server directory
cd Nitrox.Server.Subnautica

# Start server with default world
./Nitrox.Server.Subnautica

# Start server with specific save name
./Nitrox.Server.Subnautica --save "My Custom World"

# Alternative syntax
./Nitrox.Server.Subnautica --name "My Custom World"
The server executable name may vary by platform. On Windows, use .exe extension.

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Command Line Arguments

ArgumentDescriptionExample
--save <name>Specify save world name--save "Ocean Base"
--name <name>Alternative to --save--name "Ocean Base"
--embeddedRun in embedded mode (for launcher)--embedded

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Server Startup Process

When the server starts, it:
1

Finds Subnautica Installation

Locates your Subnautica game files (required for game data).Source reference: Program.cs:82-86
if (!GameInstallationFinder.FindGameCached(GameInfo.Subnautica))
{
    throw new DirectoryNotFoundException("Could not find Subnautica installation.");
}
2

Checks Port Availability

Waits up to 30 seconds for the configured port to become available.Source reference: Program.cs:99-104
3

Initializes World

Loads or creates the world save from %AppData%/Nitrox/saves/ directory.
4

Starts Listening

Binds to the UDP port and begins accepting connections.Default port: 11000 UDP

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Networking Setup

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Port Forwarding

For players outside your local network to connect, you need to forward the server port:
1

Identify Your Server Port

Check your server.cfg file for the ServerPort setting (default: 11000).
2

Configure Router

Forward UDP port 11000 (or your custom port) to your server’s local IP address.
Windows:
ipconfig
Look for “IPv4 Address” under your active network adapter.Linux/macOS:
ip addr show
# or
ifconfig
3

Enable UPnP (Optional)

If your router supports UPnP and you have AutoPortForward enabled in your config, Nitrox will attempt automatic port forwarding.
AutoPortForward=true
UPnP automatic port forwarding is enabled by default. Check your server logs to see if it was successful.

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Firewall Configuration

Ensure your firewall allows incoming UDP traffic on the server port: 
netsh advfirewall firewall add rule name="Nitrox Server" dir=in action=allow protocol=UDP localport=11000

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Finding Your Server IP

Players need your IP address to connect: Local Network (LAN):
  • Use your local IP address (e.g., 192.168.1.100)
  • Players on the same network can connect directly
  • LAN discovery is enabled by default (LANDiscoveryEnabled=true)
Internet (WAN):
Your public IP may change over time if you don’t have a static IP from your ISP. Consider using a dynamic DNS service for consistent addressing.

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Server Management

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Console Commands

Once running, you can use console commands to manage the server: 
# Display available commands
help

# Save the world
save

# Create a backup
backup

# List connected players
list

# Change admin password
changeadminpassword <new_password>

# Stop the server
stop
Type help in the server console to see all available commands.

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Graceful Shutdown

To properly stop the server:
1

Save Progress

Type save to ensure all recent changes are written to disk.
2

Stop Server

  • Console: Press Ctrl+C or Ctrl+D
  • Launcher: Click the “Stop Server” button
  • The server will automatically save before shutting down

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Save File Location

Server saves are stored in: 
%AppData%\Nitrox\saves\<World Name>\
Each save folder contains:
  • server.cfg - Server configuration
  • WorldData.nitrox or WorldData.json - World state
  • PlayerData.nitrox or PlayerData.json - Player information
  • Version.nitrox or Version.json - Save version info

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Performance Optimization

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Entity Cache Pre-loading

For better player experience when entering new areas: 
CreateFullEntityCache=true
This makes the initial server start take several minutes (loads all 504,732 entities), but improves performance when players explore new areas. Only enable this if you have time for a long initial load.
Source reference: Server.cs:203-217 
if (serverConfig.CreateFullEntityCache)
{
    Log.Info("Starting to load all batches up front.");
    Log.Info("This can take up to several minutes...");
    worldEntityManager.LoadAllUnspawnedEntities(serverCancelToken);
}

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Auto-Save Configuration

Adjust save frequency to balance safety vs. performance: 
# Save every 2 minutes (default is 120000ms)
SaveInterval=120000

# Disable autosave (not recommended)
DisableAutoSave=false

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Troubleshooting Startup Issues

Error: Port 11000 UDP is already in useSolution:
  • Close any other Nitrox server instances
  • Change the ServerPort in your config
  • Check for other applications using the port: 
    # Windows
netstat -ano | findstr :11000

# Linux/macOS
lsof -i :11000
Error: Could not find Subnautica installationSolution:
  • Ensure Subnautica is installed
  • Set the game path in the launcher
  • Verify the installation directory is valid
Possible causes:
  • Port forwarding not configured correctly
  • Firewall blocking connections
  • Wrong IP address provided to players
  • Server and client version mismatch
See Troubleshooting for detailed solutions.

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Next Steps

Configuration

Customize your server settings

Joining a Game

Learn how players connect to your server

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