BeaconServer

BeaconServer is the open-source host supervisor for Beacon multiplayer in Subnautica 2. It starts and watches the hosted game process, tracks saves, exposes admin APIs, answers Source query, and runs RCON.

BeaconServer is not the full product by itself. Players still join with the Beacon client app, and playable hosts should install the server package from the Beacon release page.

Features

🖥 Host supervision

Starts Subnautica 2 with the Beacon runtime, monitors the game process, tracks plugin heartbeat, and coordinates restarts.

💾 Save snapshots

Creates scheduled and admin-triggered snapshots. Restore swaps the save atomically so a failed restore does not leave a half-written world.

📡 Source query

Answers standard Source A2S query on the configured query port so monitoring tools can read server name, map, player count, and player list.

🛠 Source RCON

Runs a Source-compatible RCON listener for help, status, players, ping, save snapshot, and save list.

🔐 Admin HTTP API

Exposes snapshot, restore, transfer, health, and roster endpoints signed with the server's admin password.

🧩 Mod surface

Loads UE4SS Lua and C++ mods through the Beacon runtime layout.

Requirements

• Windows 10/11 or Windows Server x64
• Subnautica 2 installed on the host machine
• A Beacon release package from HumanGenome/Beacon
• Open/forwarded ports for gameplay, query, RCON, and admin HTTP as needed

Release builds are self-contained; a separate .NET install is not required for normal use.

Installation

Managed hosting

SurvivalServers.com Subnautica 2 hosting ships Beacon already installed and handles ports, updates, and panel integration.

Self-host

1. Download Beacon-Server-Windows-x64-v<version>.zip from the Beacon latest release.
2. Extract it somewhere stable, such as C:\Beacon\.
3. Edit BeaconServer\appsettings.json.
4. Open/forward the ports listed below.
5. Run BeaconServer\BeaconServer.exe.

Players connect with the Beacon client app to <host>:<GameplayPort>.

Server Settings

BeaconServer reads BeaconServer\appsettings.json under the Beacon section.

Setting	Default	Purpose
InstanceId	default	Stable instance name used in logs and generated defaults.
ServerName	empty	Public name shown in Beacon and Source query. Empty falls back to the instance id.
SnInstallRoot	C:\Beacon\game	Subnautica 2 install folder containing Subnautica2.exe.
SnUserDir	C:\Beacon\userdir	User directory used by the hosted game process.
SaveDir	C:\Beacon\saves	Snapshot metadata and archived saves.
GameplayPort	27015	UDP port players join through Beacon.
QueryPort	27017	UDP Source A2S query port.
RconPort	27018	TCP Source RCON port. RCON is disabled when RconPassword is empty.
HttpPort	27019	TCP admin HTTP API port. Set to 0 to disable.
RconPassword	empty	Admin password for RCON and HTTP signing. Set this before exposing RCON or HTTP.
ServerPassword	empty	Optional join password players enter in Beacon.
MaxPlayers	4	Slot count reported to Beacon and query clients.
SnapshotsEnabled	true	Enables automatic save snapshots and restore support.
PluginHeartbeatTimeoutSeconds	30	Seconds before BeaconServer treats the game runtime as unresponsive.

Keep the ports unique for each server instance. The standard layout is:

Port	Protocol	Purpose
GameplayPort	UDP	Subnautica 2 gameplay
GameplayPort + 2	UDP	Source A2S query
GameplayPort + 3	TCP	Source RCON
GameplayPort + 4	TCP	Admin HTTP API

Source Query Example

BeaconServer answers standard Source A2S queries on QueryPort.

py -m pip install python-a2s
@'
import a2s

address = ("127.0.0.1", 27017)
info = a2s.info(address)
players = a2s.players(address)

print(f"{info.server_name} - {info.player_count}/{info.max_players} on {info.map_name}")
for player in players:
    print(f"{player.name} {player.duration:.0f}s")
'@ | py -

The same port works with tools such as GameDig, LGSM monitors, and Discord status bots that support Source query.

RCON

Connect to RconPort with the configured RconPassword.

status
help
players
ping
save snapshot
save list

See docs/ADMIN.md for the HTTP API signing recipe and full admin endpoint list.

Build From Source

git clone https://github.com/HumanGenome/BeaconServer.git
cd BeaconServer
dotnet build BeaconServer.sln -c Release
dotnet test BeaconServer.sln -c Release --no-build
dotnet publish src/server/BeaconServer/BeaconServer.csproj -c Release -r win-x64 --self-contained true

Published output lands under src/server/BeaconServer/bin/Release/net8.0/win-x64/publish/.

Community Note

Beacon is a community project and is not affiliated with or endorsed by the developers of Subnautica 2.

Contributing

Issues and pull requests for BeaconServer are welcome. For bug reports, include the BeaconServer version, Subnautica 2 build, and relevant logs from logs\beaconserver-*.ndjson.

License

MIT. See LICENSE.

Credits

• UE4SS — Unreal Engine scripting and modding framework