A Sons of the Forest dedicated server keeps your island running on its own machine, so up to 8 players can drop in and build without the host having to be online. Endnight’s server app (Steam app 2465200) is a free download, even anonymously through SteamCMD. It needs three UDP ports open (8766, 27016 and 9700) and is configured in a JSON file called dedicatedserver.cfg. This guide walks through the setup, the self-test that stops most first attempts, every setting, admin access, saves and Kelvin, Linux and Docker, and the fixes for “could not start” and “stuck joining”.
What is a Sons of the Forest dedicated server?
It’s the same multiplayer game you’d host from the menu, but running as its own program instead of inside a player’s game. Dedicated servers arrived with Patch 07: its release on 23 June 2023 was the first version with server support. The world stays up when the host logs off, you control who can join, and nobody’s gaming PC has to carry the island while they play.
| Hosted from the game | Dedicated server | |
|---|---|---|
| Players | Up to 8 | Up to 8 (MaxPlayers, 1 to 8) |
| Host has to be playing? | Yes | No |
| World keeps running when the host leaves | No | Yes |
| Admin tools | Host only | Server owners, plus the admins they promote |
| Configured in | The game menu | dedicatedserver.cfg |
The 8-player cap is the game’s own limit.
Sons of the Forest server requirements
Give the server 8 to 12 GB of RAM on its own. That’s on top of whatever the game needs if you play on the same PC. Terrain edits and structures stay in the save and pile up, so a world that runs fine in week one needs more memory a month in. Add a CPU with decent single-core speed, an SSD, and a public IPv4 address. IPv6 isn’t officially supported.
- RAM: 8 GB is the floor, 12 GB or more for a long-running world with big bases. The Docker image maintainers list 8 GB+ as the minimum and 16 GB+ as recommended.
- CPU: 2 to 4 cores at minimum, 4 or more fast cores recommended.
- Storage: 12 GB or more, ideally an SSD with 20 GB free.
- OS: Windows. The server is a Windows program (
SonsOfTheForestDS.exe); Linux needs Wine, covered below. - Network: a static public IPv4 and three UDP ports you can forward.
How to set up a Sons of the Forest dedicated server
Setting up a Sons of the Forest dedicated server takes four steps. Download it from Steam Tools or SteamCMD, forward three UDP ports, start it once so it writes its config files, then get it past the built-in self-test. The self-test is the step that decides whether your server starts at all, so it gets its own section.
1. Download the server
From Steam: the Sons Of The Forest Dedicated Server app is in the Tools section of your library. Or download it with SteamCMD, which needs no Steam account at all:
steamcmd.exe +force_install_dir "c:/sons-dedicated/" +login anonymous +app_update 2465200 validate +quit2465200 is the dedicated server’s own app ID, separate from the game’s, and it’s the number SteamCMD needs.
2. Forward the three ports
| Port | Protocol | Used for | Config key |
|---|---|---|---|
| 8766 | UDP | Gameplay traffic | GamePort |
| 27016 | UDP | Steam server list and discovery | QueryPort |
| 9700 | UDP | BlobSync: sets up game systems and exchanges data when you join | BlobSyncPort |
Add port forwarding rules for all three on your router, and allow them through Windows Firewall. If you change a port in the config, forward the new number.
3. Start it once so it creates its files
Run StartSOTFDedicated.bat from the install folder, or press Play on the Steam tool. The first start creates the config files in the user data folder, and they don’t exist until then:
C:\Users\<you>\AppData\LocalLow\Endnight\SonsOfTheForestDS\Inside you’ll find:
dedicatedserver.cfg: the server configuration (JSON)ownerswhitelist.txt: who owns the serverSaves: the world savesSonsGameSettings.cfg: game client-style settings you normally don’t touch
You can point the server at another folder with -userdatapath "c:/path/to/directory". That’s worth doing if you want the saves somewhere you back up.
4. Pass the self-test
Every time it boots, the server tests its own config and network. If any test fails, the server won’t start, and the console or log says why. This is where most first setups stop.
| Self-test message | What to do |
|---|---|
| Server configuration doesn’t exist. A default one has been created | Normal on the first run. Edit dedicatedserver.cfg if you want, then restart |
| Server owners whitelist doesn’t exist | Also normal the first time. Add your SteamID (below) and restart |
| The configuration couldn’t be read without error | Your JSON is broken: a missing comma, quote or bracket |
| Error about a value | A setting is out of range; the console names which one |
| Failed to get public ip from Steam | You need a valid static public IPv4 |
| UDP <PortName> <PortNumber> is closed | Port forwarding or firewall: fix the rule for that port |
If the network test keeps failing, you have three options. Fix the port forwarding. Set "LanOnly": true to hide the server from the internet and play on your home network. Or, experts only, set "SkipNetworkAccessibilityTest": true. Endnight warns that a server failing the test usually isn’t reachable anyway. Skipping it is mainly for routers without NAT loopback (hairpin NAT), where the server can’t test itself through its own public IP. If skipping doesn’t help, set it back to false.
Sons of the Forest dedicated server settings (dedicatedserver.cfg)
dedicatedserver.cfg is a JSON file, so formatting matters. Text values go in quotes; numbers and true/false don’t. Every line except the last needs a comma. Any key you leave out uses its default. Here’s the default file:
{
"IpAddress": "0.0.0.0",
"GamePort": 8766,
"QueryPort": 27016,
"BlobSyncPort": 9700,
"ServerName": "Sons Of The Forest Server (dedicated)",
"MaxPlayers": 8,
"Password": "",
"LanOnly": false,
"SaveSlot": 1,
"SaveMode": "Continue",
"GameMode": "Normal",
"SaveInterval": 600,
"IdleDayCycleSpeed": 0.0,
"IdleTargetFramerate": 5,
"ActiveTargetFramerate": 60,
"LogFilesEnabled": false,
"TimestampLogFilenames": true,
"TimestampLogEntries": true,
"SkipNetworkAccessibilityTest": false,
"GameSettings": {},
"CustomGameModeSettings": {}
}| Setting | What it does |
|---|---|
ServerName |
Name in the server list and in Steam contacts |
MaxPlayers |
Players at once, 1 to 8 |
Password |
Makes the server private; up to 40 characters |
LanOnly |
Hide from the internet list and play on LAN only |
SaveSlot |
The save slot number the server creates or loads (1 or higher) |
SaveMode |
continue loads the slot, or creates it if empty. new starts a fresh world and overwrites that slot on every restart while it’s set |
GameMode |
Difficulty for a new save: normal, hard, hardsurvival, peaceful, creative or custom. Ignored when loading an existing save |
SaveInterval |
Seconds between autosaves (600 = every 10 minutes) |
IdleDayCycleSpeed |
How fast time passes with nobody online (0 freezes it, 1 is normal) |
IdleTargetFramerate / ActiveTargetFramerate |
Server frame rate when empty (default 5) and with players on (default 60) |
LogFilesEnabled |
Write logs to <user data folder>/logs. Off by default; turn it on |
SkipNetworkAccessibilityTest |
Skip the network self-test (expert only, see above) |
GameSettings |
Settings that work in any mode: "Gameplay.TreeRegrowth" and "Structure.Damage" |
CustomGameModeSettings |
Custom-mode rules, read only when GameMode is custom and a new save is created |
Custom game mode settings
To make your own rules, set "GameMode": "custom" and fill in CustomGameModeSettings before the world is created. These are locked in when the save is made, so changing them later on a running world does nothing.
"CustomGameModeSettings": {
"GameSetting.Multiplayer.Cheats": false,
"GameSetting.Vail.EnemySpawn": true,
"GameSetting.Vail.EnemyAggression": "Normal",
"GameSetting.Environment.StartingSeason": "Summer",
"GameSetting.Environment.SeasonLength": "Default",
"GameSetting.Environment.DayLength": "Default",
"GameSetting.Survival.ColdPenalties": "Off",
"GameSetting.Survival.BuildingResistance": "Normal",
"GameSetting.Survival.OneHitToCutTrees": false
}Enemy health, damage, armour and aggression take low, normal or high. Season and day length take short, default, long or realistic. There are also switches for creative mode, god mode for all players, cheats, single-use containers and reduced food in containers.
Overriding settings from the command line
Any setting can also go on the launch line, which is handy for a second server or for testing:
SonsOfTheForestDS.exe -dedicatedserver.ServerName "Our Island" -dedicatedserver.MaxPlayers "4"Add -verboseLogging when you’re chasing a problem; leave it off otherwise, as it makes the logs much bigger. Don’t edit StartSOTFDedicated.bat itself, because updates overwrite it. Make a copy.
Sons of the Forest dedicated server admin
Admin rights come from ownerswhitelist.txt in the user data folder. Put the SteamID64 of each server owner on its own line, and only add people you trust: owners have the same rights as the host of a normal game.
# Server owners, one SteamID64 per line
76561198000000000Find your SteamID on your Steam account details page. Restart the server, join, and open Pause Menu → Players. From there, owners can promote players to admin, demote them to guests, kick guests, and ban or unban them. Endnight’s guide documents no separate chat admin commands for dedicated servers; administration runs through that panel.
How to join your server
- Start Sons of the Forest and choose Multiplayer, then Join.
- Switch the browser’s source to Dedicated and search for your server’s name.
- Join and enter the password if you set one.
If you play on the same network as the server and your router doesn’t support NAT loopback, the server may not appear in the dedicated list for you. You can only join it from the LAN browser. Friends outside your home still see it normally.
Saves: location, moving a world, and Kelvin
The server keeps its saves in the Saves folder inside the user data folder (or under your -userdatapath). Back up that whole folder before every update and before you try anything risky. It holds the world, the buildings and everyone’s progress.
To continue a co-op world on the server, stop the server and copy the world’s folder from your PC (%USERPROFILE%\AppData\LocalLow\Endnight\SonsOfTheForest\Saves\) into the server’s Saves folder, at the slot the server uses (SaveSlot). Keep SaveMode on continue. With new, the server would overwrite it on the next start. Test with a copy first, and keep the original.
Can you revive Kelvin on a dedicated server? The reliable way back is a backup. If Kelvin dies, stop the server and restore the save from before it happened. A short SaveInterval plus regular copies of the Saves folder is what makes that possible. If your only backup is a week old, you lose a week.
Sons of the Forest dedicated server on Linux and Docker
Endnight only ships a Windows build. On Linux, people run it under Wine, and the simplest way is a ready-made Docker image such as jammsen/docker-sons-of-the-forest-dedicated-server, which bundles Wine and SteamCMD and updates the server on start:
services:
sons-of-the-forest-dedicated-server:
image: jammsen/sons-of-the-forest-dedicated-server:latest
restart: always
environment:
PUID: 1000
PGID: 1000
ALWAYS_UPDATE_ON_START: true
SKIP_NETWORK_ACCESSIBILITY_TEST: true
ports:
- 8766:8766/udp
- 27016:27016/udp
- 9700:9700/udp
volumes:
- ./game:/sonsoftheforestThe config ends up in game/userdata/dedicatedserver.cfg. Wine prints a lot of harmless warnings about shaders. The image filters most of them out of the log. If you’d rather not run Wine at all, Sons of the Forest server hosting runs the server for you.
Updating the server
When the game updates, a server on the old version won’t let players in. Stop it, back up the Saves folder, run the same SteamCMD line again (app_update 2465200 validate), or let Steam update the tool, then start it.
Can you add mods?
Sons of the Forest has no official mod support for dedicated servers. Community mod loaders exist, but Endnight doesn’t support them, and a game update can break them overnight. Run vanilla if you want a server that just works after every patch.
Common Sons of the Forest server problems and fixes
| Problem | Likely cause | Fix |
|---|---|---|
| Server could not start / closes on launch | A self-test failed | Read the console or log; the reason is printed there (see the self-test table) |
| “UDP … is closed” / ports closed | Port forwarding or firewall | Forward 8766, 27016 and 9700 UDP to the server’s local IP |
| Dedicated server not showing up | Query port blocked, LanOnly on, or no NAT loopback on your network |
Check 27016, set LanOnly to false, or join from the LAN browser at home |
| Stuck on “joining game server” | BlobSync traffic blocked, or client and server on different versions | Check UDP 9700, then update both the game and the server |
| Crashing when joining the server | Out of memory on the server or the client, or a version mismatch | Give the server more RAM, update, and check the server log for errors |
| Settings ignored | Broken JSON, or a CustomGameModeSettings change on an existing save |
Validate the JSON; custom rules only apply when a new save is created |
| World resets every restart | SaveMode left on new |
Set it to continue |
| Invalid password | Password mismatch or a typo in the JSON | Re-type Password in the config and restart |
| Server down after a game patch | Old server build | Update with app_update 2465200 validate |
Turn on LogFilesEnabled before you need it. A server that crashed overnight with logging off leaves you guessing. Advice on Reddit and the Steam forums often starts with “disable the self-test”. Fix the ports first; the test is usually right.
Skip the setup: rent a Sons of the Forest server
Hosting it yourself means a Windows PC that stays on, three forwarded ports, a self-test that refuses to start until all of it is right, and a config file that doesn’t exist until the first run. If your group would rather just survive the island, Sons of the Forest server hosting on GameTeam is up in minutes with nothing to forward. You pay per GB of RAM with unlimited slots (the 8-player cap is the game’s own), from $0.49/GB a week on Budget or $1.99/GB billed monthly. A 12 GB server for a long-running world is $5.88 a week.
The built-in AI copilot does the fiddly parts. Tell it “make the server private with the password cannibals, turn on tree regrowth and keep time frozen when nobody’s on” and it edits dedicatedserver.cfg, checks the JSON is still valid and restarts the server. If the island went dark overnight, ask it what happened: it checks the server log and explains the failure in plain words. Ask it to back up the save before you go after the final boss, and you have a restore point if Kelvin doesn’t make it. Weekly billing fits a game most groups play hard for a few weeks, there’s a 72-hour money-back window, and the server can switch to your next game when you leave the island.
FAQ
Is the Sons of the Forest dedicated server free?
The server app is a free download from Steam Tools or SteamCMD (app 2465200), no account needed with SteamCMD. You pay for the machine it runs on, or for hosting.
How many players can join a Sons of the Forest dedicated server?
Up to 8. MaxPlayers accepts 1 to 8, and that limit is set by the game.
What ports does a Sons of the Forest dedicated server use?
UDP 8766 (game), 27016 (query) and 9700 (BlobSync). All three need to be open.
Where is the Sons of the Forest server config?
dedicatedserver.cfg in C:\Users\<you>\AppData\LocalLow\Endnight\SonsOfTheForestDS\, or in the folder you set with -userdatapath. It appears after the first start.
How do I start Sons of the Forest multiplayer on a dedicated server?
Choose Multiplayer, then Join, switch the source to Dedicated and pick your server. The host doesn’t need to be online.
Why does Sons of the Forest crash when I join a server?
Usually a version mismatch after a patch, or the server or your PC running out of memory. Update both, then check the server log. If the server is the one struggling, give it more RAM.
Can I run a Sons of the Forest server on Linux?
Not natively. The official server is Windows-only, but it runs on Ubuntu and other distros under Wine, most easily through a Docker image.
Can I change settings on an existing world?
Server settings such as the name, password, player count and save interval, yes: edit the file and restart. Custom game mode rules are different. They’re read only when a new save is created, so they’re locked in for that world.