Updated 10 October 2026
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Nitrox is the open-source mod that adds multiplayer to Subnautica, and hosting a game takes three things: the Nitrox Launcher, a started server and UDP port 11000 reachable from the internet. The current release is 1.8.1.0, published on 7 January 2026 and still labelled an early alpha on the official download page. One server takes up to 100 players, although the Nitrox team suggests about five for the smoothest game. This guide walks through installing the mod, starting and opening the server, tuning server.cfg, using admin commands and keeping saves safe, with every detail taken from the Nitrox site, its release notes and its source code.
Before you start
- Everyone needs the game. Each player installs Nitrox on top of their own copy of Subnautica and points the launcher at that game folder.
- Only the final game version works. Nitrox 1.8.0.0 dropped support for every older build of Subnautica and supports only the final version, the 2025 patch; the team’s blog adds that Unknown Worlds removed older versions of the game because of a Unity security flaw.
- Stores and systems: releases from 1.8.0.1 on support the Steam, Epic Games and Microsoft Store versions, and the website notes that the Microsoft Store version needs extra setup explained on the Nitrox Discord. Builds exist for Windows and for Linux on x64 and ARM64; Linux support began as experimental in 1.8.0.0, and a macOS version is planned for later.
- Matching versions: the launcher warns when versions differ. Saves made with 1.8.1.0 still load in 1.8.0.0 and 1.8.0.1, but everyone should run the same release.
Step 1: install Nitrox
- Download the latest release from the official Nitrox website; the Windows package is about 25 MB.
- Unzip it into the folder where the launcher should live. The install guide warns against starting it from inside the zip, because progress will not save and more bugs appear.
- Run NitroxLauncher as administrator.
- Open Options, choose Change and select your Subnautica folder, for example C:\Program Files\Epic Games\Subnautica for Epic or C:\Program Files\Steam\steamapps\common\Subnautica for Steam.
Since 1.8.1.0 the launcher also recognises the Heroic Games Launcher on Windows and Linux and standalone installs of the game, and it shows a warning when BepInEx mods are present.
Step 2: start the server
In the launcher, open Server and choose Start Server. The server window then lists the game mode, the server password, the admin password, your local IP for LAN play and the address other players should type when your port is forwarded. The 1.8 launcher can manage several servers, change their settings and restore backups of each world, and with the IsEmbedded setting left on, the server runs inside the launcher rather than in a separate window.
Step 3: open UDP port 11000
The official server guide says Nitrox uses port 11000 over UDP, and players outside your network can only reach it through an open port. There are three ways to get there:
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- Automatic UPnP: AutoPortForward is on by default in server.cfg, so the server asks a compatible router to open the port by itself.
- Manual forwarding: forward UDP 11000 on your router to the PC running the server.
- A VPN: the guide names Hamachi as an option for people who cannot or would rather not forward ports.
If people still cannot connect, the host and the players should all add firewall exceptions for Subnautica.exe and NitroxServer-Subnautica.exe. Release 1.8.1.0 added IPv6 support, and LAN discovery is on by default for players on the same network.
Step 4: let players join
- Each player opens the Nitrox Launcher as administrator and selects Multiplayer.
- They choose Add server IP, type a name for the server and the host’s address, and confirm with Add server.
- They select the server in the list, connect, enter a username, choose a colour and press Join.
The host takes the address from the server window, and players joining over the internet need the public one, not the LAN address.
Step 5: tune server.cfg
Nitrox keeps its settings in a file called server.cfg. These are the defaults in the 1.8.1.0 source code:
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| Setting | Default | What it does |
|---|---|---|
| ServerPort | 11000 | Port the server listens on |
| MaxConnections | 100 | Most players allowed at once; must be above 0 |
| ServerPassword | Empty | Password players type to join |
| AdminPassword | Random, 12 characters | Unlocks admin rights through the login command |
| GameMode | SURVIVAL | Also FREEDOM, HARDCORE or CREATIVE |
| Seed | Blank | Blank gives a random spawn position |
| SaveInterval | 120000 | Autosave interval in milliseconds, at least 1000 |
| MaxBackups | 10 | How many backups the server keeps |
| KeepInventoryOnDeath | false | Players keep their items when they die |
| PvPEnabled | true | Player-versus-player damage and interactions |
| DefaultPlayerPerm | PLAYER | Permission level new players get |
| LocalhostIsAdmin | true | Gives admin to players on localhost; turn off behind a proxy |
| SafeBuilding | true | Rejects building actions detected as out of sync |
| AutoPortForward | true | Tries to open the port through UPnP |
A few more switches are worth knowing. CreateFullEntityCache builds an entity cache for the whole map on the next start, which makes that start slower but helps players entering new areas. DisableAutoSave, DisableAutoBackup and DisableConsole do what their names say, and PostSaveCommandPath can run a program or script after every successful save, which is handy for copying saves elsewhere. New players also start with the stats set in the file: 45 oxygen, 80 health, 50.5 food, 90.5 water and an infection value of 0.1, which the file suggests leaving as it is.
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Nitrox has four practical permission levels. PLAYER, the default, covers basic commands such as help, list and whisper. MODERATOR adds vanilla cheat commands and tools like mute, kick and broadcast. ADMIN can change server settings and other players’ rights, and the server console holds every permission. To become admin in game, type login with the admin password from the server window; an admin can then grant the role to others with op.
| Command | Level | Use |
|---|---|---|
| login <password> | Player | Log in as admin |
| list / whisper | Player | See who is online; send a private message |
| save | Moderator | Save the map now |
| kick / mute / unmute | Moderator | Remove or silence a player |
| time day / night | Moderator | Change the time of day |
| teleport / warp / back | Moderator | Move to coordinates, move players, return to the last spot |
| promote | Moderator | Set a player’s permission level |
| op / deop | Admin | Give or remove admin rights |
| backup | Admin | Create a backup of the save |
| autosave on / off | Admin | Toggle autosaving |
| pvp / keepinventory | Admin | Switch PvP or item keeping on death |
| changeserverpassword | Admin | Change the join password, or clear it |
| aurora / sunbeam | Admin | Control the Aurora’s state and the Sunbeam story events |
| stop | Admin | Shut the server down |
Game modes work at two levels. GameMode in server.cfg sets the mode the world starts in, an admin can switch the whole server later with changeservergamemode, and gamemode changes the mode of a single player. From the server console, config opens server.cfg and directory opens the server’s folder, which helps when you are looking for saves. Saves use the JSON format by default, and the console-only swapserializer command changes it. Moderators also get broadcast for announcements to everyone and summary, which shows the data the server has stored.
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Saves, backups and a server without a desktop
With the defaults, the world saves every two minutes and the server keeps up to ten backups, which the launcher can restore. The Nitrox team’s release blog asks Linux hosts to take backups now and then, which makes a copy routine through PostSaveCommandPath worth setting up. For a server on a machine without the launcher, release 1.8.0.1 added a –game-path argument that points the server at a Subnautica installation, as an alternative to the SUBNAUTICA_INSTALLATION_PATH environment variable, and a –data-path argument that sets where logs, cache and saves go; 1.8.1.0 fixed that second argument and a DirectoryNotFound error that could stop the server from starting.
What changed in Nitrox 1.8
Version 1.8.0.0 arrived on 9 October 2025, the first major release since 1.7.0.0 in December 2022, and its developers rewrote most of the mod from scratch to cope with Subnautica’s 2.0 update. For anyone returning from 1.7.1.0, these changes matter most:
- Building: a new building system with sync for the newest base pieces, fixes for several corruption bugs and short cooldowns that stop two players from overwriting the same base at once.
- Story: extra sync for the radio, lifepod signals, the Sunbeam, the Aurora, radiation and leaks; radiation leaks you have fixed stay fixed after reconnecting.
- Movement: smoother vehicle sync that adapts to each player’s latency, and players can walk around a moving Cyclops without being thrown out of it.
- World and creatures: a shared sky, so eclipses happen for everyone at once, plus respawning fish, plant growth and harvesting, geyser eruptions and Reaper, Ghost and Sea Dragon leviathans.
- Players: two players can watch the introduction cinematic together, crafting pins and quick slots persist, and keep-inventory and knife-PvP settings arrived with commands to match.
Fixing common problems
- Friends time out: confirm UDP 11000 is forwarded or that UPnP worked, and that the host and players have allowed Subnautica.exe and NitroxServer-Subnautica.exe through their firewalls.
- The launcher misbehaves: check that it was unzipped first and runs as administrator, as the install guide asks.
- Version warnings: everyone needs the same Nitrox release on the final game version.
- Other mods: the launcher flags BepInEx mods with a warning since 1.8.1.0, so test a world without them first.
- A headless server will not start: point it at the game files with –game-path or SUBNAUTICA_INSTALLATION_PATH, and update to 1.8.1.0, which fixed a DirectoryNotFound start-up error.
- Everyone becomes admin behind a proxy: set LocalhostIsAdmin to false, the option 1.8.1.0 added for exactly this case.
- Anything else: the README sends issue reports to the Nitrox Discord, where the team takes on new issues to track.
What Nitrox does not sync yet
The 1.8.1.0 release notes list four known issues: story PDAs and terminals are not synced, Discord integration does not work outside Windows, creatures other than leviathans are not fully synced, and oxygen tanks show as empty in the inventory after a player reconnects. The same release added sync for the Exosuit’s arms, drillable mineral deposits, ion cube deposits and the Cyclops decoy upgrade, and improved the join queue so crashes during loading cause fewer problems.
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Renting a Nitrox server instead
Godlike.Host sells Subnautica Nitrox servers sized by memory. Its Nitrox page, read on 10 October 2026, shows three plans, 2 GB (Ultra), 4 GB (Unstoppable) and 6 GB (Rampage), and a custom option spanning 2 to 33 GB of memory with 4 to 200 player slots. The servers run on Ryzen hardware and install automatically right after payment.
The page names a control panel of its own, extra ports for each server, DDoS protection, full SFTP access, expert support and a daily allowance of three free backups, and it says servers can be handled through the company’s Discord community as well. With SFTP, an existing world can be uploaded and server.cfg edited by hand.
Limit: the Nitrox page does not say which Nitrox or Subnautica version its servers run, so confirm 1.8.1.0 on the final game version with support before moving a world, and the free backups stop at three per day.
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FAQ
Is Nitrox an official Subnautica feature?
No. It is a community-made, open-source mod released under the GPL v3 licence, and the team says public servers are not hosted or moderated by Nitrox.
How many people can play on one Nitrox server?
Up to 100, the MaxConnections default, though the website suggests about five players for the steadiest game.
Which port does Nitrox use?
UDP 11000 unless you change ServerPort in server.cfg.
Does Nitrox work with older versions of Subnautica?
Not since 1.8.0.0. The current releases support only the final version of the game.
How do I become admin on my own server?
Players on the host machine get admin automatically while LocalhostIsAdmin is on; anyone else types login followed by the admin password shown in the server window.
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