Self-Host Colyseus Behind NAT with Localtonet

What this self-hosted architecture does

Colyseus is an authoritative multiplayer framework for Node.js. In an authoritative design, important game state and game rules run on the server rather than being accepted directly from a player. Clients send actions or inputs, while the server decides how those actions affect the shared state. Colyseus provides room-based gameplay, matchmaking, reconnection support, and synchronizable data structures for real-time and turn-based projects.

A typical Colyseus client first uses an HTTP-based matchmaking operation such as joining or creating a room. The connection can then use WebSockets for persistent, bidirectional communication with that room. This means remote access must account for more than an ordinary page load. The public endpoint must handle the initial HTTP requests and the WebSocket upgrade and connection used by the game session.

Self-hosting introduces a networking boundary. A server listening on a laptop, workstation, home server, or private cloud instance may be accessible only from that machine or its local network. Network address translation commonly prevents unsolicited inbound internet traffic from reaching it. Carrier-grade NAT, changing public addresses, and restrictive network environments can make conventional router forwarding unavailable or inconvenient.

With Localtonet, the client application on the machine that can reach Colyseus establishes an outbound connection to one of our relay servers. An HTTP tunnel points to the Colyseus local IP address and port and provides a public URL. The tunnel remains available only while the selected Localtonet client is connected and the tunnel is running.

Prerequisites and decisions to make first

The official Colyseus quickstart requires Node.js and uses npm. Install a currently supported Node.js release from the official Node.js distribution appropriate for your operating system. The supplied Colyseus evidence does not establish a specific minimum Node.js version, so this guide does not invent one. If your project or the current Colyseus documentation specifies a version, follow that requirement and keep it consistent across development and deployment.

Confirm that both Node.js and npm are available in your terminal:

node --version
npm --version

Both commands should print version information. If either command is missing, repair the Node.js installation or terminal path before creating the project. A package manager error at this stage is unrelated to NAT or Localtonet and should be resolved locally first.

You also need a directory where the generated project can be created, permission to install its dependencies, and a terminal that can keep the server process running. For remote access, install and run the Localtonet client on the same machine as Colyseus or on a device that can reach the Colyseus listening address over the local network.

Before continuing, decide whether this is a temporary development endpoint or a persistent deployment. A development machine is suitable for controlled testing, but it may sleep, restart, change networks, or stop the terminal process. A long-running game service needs deliberate process supervision, updates, backups, resource monitoring, and an application-specific security plan. Those production controls are distinct from tunnel creation.

Install and start a Colyseus server

The official quickstart provides a compact three-command workflow. Run it from the parent directory in which you want the new my-server directory to be created.

npm create colyseus-app@latest ./my-server
cd my-server
npm start

The generator may ask questions or offer presets depending on its current release. Select options that match the type of game you are building, and retain a record of those choices. Colyseus 0.18 release information identifies minimal, realtime-action, and turn-based create-colyseus-app presets, but the exact interactive prompts and resulting project contents can change. Read each prompt rather than assuming a fixed sequence beyond the official quickstart commands.

When npm start succeeds, do not immediately close the terminal. Its output is the most reliable evidence for the endpoint produced by your generated version and configuration. Look for the address or interface, the port, startup completion, and any registered development tools or routes. If the process exits, resolve that failure before configuring remote access.

The generated package.json is the authoritative record of what npm start invokes in this project. Review it before adding a production service manager or changing scripts. Also review the generated source to locate room registration, transport configuration, environment handling, and optional development interfaces. File names are intentionally not prescribed here because the supplied evidence does not establish a stable generated layout.

Configure Colyseus for your game

A generated server is a starting point, not a complete production game backend. Your application must define at least one room that corresponds to the name your client will request. Room logic owns the server-side state and receives client lifecycle events and messages. The client and server must agree on the room name, expected messages, and synchronized schema.

Define the room contract

Write down the protocol between the game client and server before exposing it. That contract includes the matchmaking room name, accepted join options, client messages, server responses, state fields, error handling, and reconnection behavior. A mismatch can resemble a networking problem even when the HTTP and WebSocket connection itself is healthy.

Colyseus supports server-authoritative state synchronization. Keep decisive game rules on the server, validate every client-supplied value, and reject actions that are impossible or unauthorized. A WebSocket connection is not proof that a player may access every room or perform every action.

Determine the actual listening endpoint

Identify the local endpoint from the generated project and runtime output. You need two values for the later tunnel configuration: a local IP address reachable from the Localtonet client device and the listening port used by Colyseus.

If both processes run on the same machine, use the local address confirmed by the application and operating system. If Localtonet runs on a different device, a loopback-only listener cannot be reached from that other device. In that topology, configure Colyseus according to its current documentation so it listens on an appropriate local interface, then test access from the Localtonet device before creating the tunnel.

Do not assume that a browser-visible URL proves the WebSocket path is correct. A Colyseus deployment can involve matchmaking routes, room connections, and optional tools. Verify the exact workflow used by your intended client SDK.

Keep development interfaces private

Generated projects or selected presets may include playground, monitoring, or administrative functionality. Colyseus 0.18 introduced guards for monitor and playground usage and changed production behavior for playground data endpoints. Review your generated version carefully. Do not expose operational tools merely because they share the same server as the game endpoint.

Verify the server locally before tunneling it

Local verification should proceed from the simplest check to the complete multiplayer workflow. The purpose is to prove that Colyseus works independently of public DNS, relay selection, and remote networks.

The last two checks are essential. A successful HTTP response can coexist with a failed WebSocket upgrade, a mismatched room name, an incompatible SDK, or an exception in room logic. Conversely, an HTTP 404 on an undocumented root path does not necessarily prove the game protocol is unavailable. Test a route and room workflow that the project actually defines.

For a two-player game, run at least two controlled clients when practical. Confirm that both join the intended room and that one client’s permitted action results in the expected state update for the other. Also test disconnect and reconnection behavior if your game depends on it.

Expose the working Colyseus endpoint with Localtonet

Once local verification succeeds, create an HTTP tunnel that points to the confirmed Colyseus address. An HTTP tunnel is the appropriate family for this workflow because the game endpoint uses HTTP interactions and WebSocket connections rather than an unrelated raw game protocol.

Localtonet runs independently of the Colyseus process. Keep Colyseus running, then install and run our client on the device that can reach it. The Localtonet client establishes an outbound relay connection, so you do not need to configure inbound router forwarding, make firewall changes, build a VPN, or obtain a public IP address.

HTTP process types provide the same content through a public HTTPS address, but their naming and DNS workflows differ. Exact custom-domain DNS instructions are not included because they must be checked against the current Localtonet documentation before configuration. For the initial test, use the public address assigned by the dashboard.

You can review the current product workflow in our Localtonet HTTP tunnel documentation. Use the dashboard’s current field labels and available relay choices rather than relying on old screenshots or hardcoded values.

Point Colyseus clients at the public endpoint

After remote verification, replace the local development base endpoint in your test client with the public HTTPS URL assigned to the Localtonet HTTP tunnel. The official Colyseus examples initialize supported clients with a server endpoint and then call a matchmaking operation such as joinOrCreate using a registered room name.

A JavaScript or TypeScript client follows this general pattern:

import { Client } from "@colyseus/sdk";

const client = new Client("https://your-assigned-public-host");
const room = await client.joinOrCreate("your_registered_room");

Replace both placeholders with values from your deployment. The host must be the public URL assigned to your running tunnel, and the room name must exactly match a room registered by your server. Do not publish a private dashboard URL, Localtonet device token, or administrative credential in client code.

Colyseus provides SDKs for multiple engines and platforms. Endpoint syntax can differ. For example, some SDK examples accept an HTTPS server URL, while another may show a secure WebSocket URL. Follow the current SDK documentation for the exact client you ship. Do not mechanically convert schemes or append guessed paths.

Test from a network genuinely outside the server’s LAN, such as a separate internet connection. Verify all of the following:

• The client reaches the public endpoint without using the private LAN address.
• The intended matchmaking request completes.
• The player joins the expected room.
• The WebSocket connection remains open during normal gameplay.
• Messages or player inputs reach the server.
• Authorized state updates return to every expected client.
• Disconnect and reconnect behavior matches the game’s design.

Browser clients may also be subject to browser security rules associated with origins, cookies, authentication, and mixed content. If the web page itself is loaded over HTTPS, use the secure public endpoint appropriate to the SDK rather than attempting an insecure connection from that page. Configure application-level origin and credential behavior deliberately if your architecture requires it.

Operate the server safely

A reachable prototype and a dependable multiplayer service have different operational requirements. Localtonet supplies public connectivity to the local target, but it does not replace application security, deployment discipline, or capacity planning.

Protect identities and secrets

Keep the Localtonet device token on the tunnel host. Keep database credentials, signing keys, administrative credentials, and private service URLs on the server side. Public game clients must contain only information they are expected to reveal, including the public game endpoint.

Authenticate players when the game requires identity. Authorize room joins using server-side information rather than trusting a client-supplied role or player identifier. Validate message types, value ranges, movement rates, ownership, and state transitions. The authoritative model is useful only when the authoritative server rejects invalid input.

Separate development and production access

Do not expose source maps, debug routes, playgrounds, monitors, profilers, or administrative consoles to ordinary players. If operational access is necessary, protect it with the controls supported by your selected Colyseus version and application architecture. Colyseus 0.18 includes guard options for monitor and playground usage and a basic authentication middleware for HTTP routes, but those capabilities still require deliberate configuration.

Plan process continuity

Both Colyseus and the Localtonet client must remain running. A closed terminal, operating system restart, sleeping laptop, lost network connection, or stopped tunnel can disconnect players. For a persistent deployment, use operating system facilities or a process manager that is suitable for your environment. The supplied evidence does not establish one required process manager or a universal service file, so those commands are intentionally not guessed here.

Define how deployments handle active rooms. Abruptly stopping the process interrupts WebSocket sessions and may lose in-memory game state. If your application needs persistence, implement and test it according to the game’s requirements. Colyseus 0.18 includes an official database package built on Drizzle ORM for SQLite or PostgreSQL use cases, but adopting it is an application architecture decision rather than a prerequisite for this basic tunnel workflow.

Monitor the complete path

Observe application exceptions, room creation failures, rejected joins, connection counts, memory, CPU, and event-loop behavior. Also monitor whether the Localtonet device and tunnel remain connected. These are different failure domains. A connected tunnel cannot make an exited Colyseus process healthy, while a healthy local server is not publicly reachable when the tunnel is stopped.

When updating Colyseus, read the migration notes for the target release. Version 0.18 includes breaking changes such as a maximum of 63 fields in a Schema, replacement behavior for metadata setters, removal of client.id in favor of client.sessionId, and authentication migration considerations. Test client SDK compatibility, serialized state, room behavior, and reconnection before updating a live deployment.

Troubleshooting Colyseus and Localtonet

Use a layered diagnosis

Start on the Colyseus host. Confirm that the process is alive and repeat the known local client test. If that fails, the tunnel is not the cause. Fix the application, dependencies, room registration, or local endpoint first.

Next, test the same endpoint from the device running Localtonet if it is a separate machine. If that fails, correct local reachability or the Colyseus listening interface. Only after both local tests pass should you inspect the Localtonet client connection, tunnel status, relay selection, and target mapping.

Finally, test from an external client and compare timestamps across the client, Colyseus logs, and Localtonet status. If no request reaches Colyseus, focus on the endpoint and tunnel path. If Colyseus receives the request and rejects it, focus on room names, authentication, authorization, SDK compatibility, and application exceptions.

Frequently asked questions