How to Play Factorio Multiplayer with Friends: Steam, LAN or a Dedicated Server

Factorio multiplayer comes in three shapes, and the one you pick decides who has to be online for the factory to exist. One player can host from their own game, which is how most groups start. Players on the same network can use LAN. Or the world can live on a dedicated server that stays up when everyone logs off. All three use the same netcode and the same save files, so you can start with one and move to another later without losing anything.

This guide covers each route in the order most groups try them, the one rule that breaks more multiplayer sessions than anything else, and how to move a world you started at home onto a server.

The rule that decides whether anyone can join

The official wiki puts it plainly: "All game instances need the installation of exactly the same game-versions and mods." A friend on a different build, or missing one mod, cannot connect. Most "can't join" problems come down to this.

Pick a Route

Factorio has used a client-server model since version 0.13. The wiki notes that "P2P connecting is completely removed." Whoever hosts acts as the server and relays everyone else's traffic. That is why the host's connection matters, and why a dedicated server is the step up when a group outgrows it.

Route 1: Host From Your Own Game

This is the quickest way to play Factorio multiplayer with friends. From the main menu choose Multiplayer, then:

• Host new game to generate a fresh world, with the usual map-generator settings, or
• Host saved game to open one of your existing saves to other players.

Either way you pick a server visibility, which the wiki describes as three independent switches:

• Public: listed in the in-game public games browser.
• Steam: enables Steam's "Join Game" feature.
• LAN: listed for players on your local network.

For a group of friends, leave Steam on and invite them through the Steam friends list. The wiki recommends this route for most players: "This is the most recommended way for the average player to use multiplayer with their friends, as it allows Steam to handle everything." Steam handles the connection, so nobody has to type an address or change anything on their router.

If someone does not own the game on Steam, they can use Connect to address instead. That only works if your machine can be reached from the internet. The wiki says that behind NAT "you must set up port forwarding", and Factorio's default port is UDP 34197. Factorio uses UDP only, so a TCP-only port-forward rule will not work.

The downside of hosting from your own game is simple. When you quit, the world goes with you, and nobody can play without you.

Route 2: LAN

If everyone is on the same network, the host ticks LAN visibility and the others use Multiplayer → Browse LAN games. There's no port forwarding and no account step, but it only works inside one network. LAN also doesn't solve the host problem: the world still lives on one player's PC.

Route 3: A Dedicated Server

A dedicated server runs the headless build of Factorio. It has no graphics and no character, and it hosts one save for as long as it's switched on. Nobody has to be in-game for the world to be available, which is what a long campaign needs.

On a GameServerKings Factorio server the install does the awkward part for you. The headless server can't start without a save, so the installer creates one from the Save Name value (gamesave by default), and the server boots straight into it. How to Set Up a Factorio Dedicated Server walks through that first boot.

Getting your group in takes four steps:

1. Set a password. Fill in Server Password on the Startup tab, or leave it blank for an open server. Use the panel field, not the file. The server copies this field into game_password in data/server-settings.json every time it starts, so a password typed straight into the file gets overwritten on the next boot. The same goes for the server name, description, username, token, autosave and AFK settings.
2. Wait for Hosting game at in the console. Until that line appears the server is still loading the map.
3. Share the address. Copy the IP and port from the Network tab. Your server has its own port, which may not be 34197, so always give players the full address:port.
4. Friends connect through Multiplayer → Connect to address.

That address works whether or not the server is listed publicly. Listing it in the public browser is optional and needs a factorio.com username and token. How to Set Up a Factorio Dedicated Server covers both.

A hostname instead of an IP

Factorio has supported DNS SRV records since 1.1.67, with service _factorio over _udp. If you own a domain, a record like _factorio._udp.play.example.com pointing at your server's port lets players connect to play.example.com with no port number.

Things that are different on a dedicated server

• The world pauses when nobody is online. The wiki says the headless server "is paused while there are no players connected". It's a deliberate default: the factory doesn't run and biters don't evolve while everyone is asleep. Turning it off is the auto_pause key in server-settings.json.
• There is no server player. Nobody stands at spawn. The first person to join lands in a world that was frozen until they arrived.
• Admins are set from the console. Run /promote <name> from the panel Console tab. Factorio console commands has the full moderation set.
• Player slots are fixed at 50. Max Players appears on the Startup tab but can't be edited.

Moving Your Existing World to the Server

Most groups don't start on a server. They play a few sessions with one person hosting, then want the world always available. The save file is the whole world, and it moves across as-is:

1. On the host's PC, find the save zip in the saves folder of Factorio's user data directory: %appdata%\Factorio\saves on Windows, ~/Library/Application Support/factorio/saves on macOS, ~/.factorio/saves on Linux.
2. Upload it to the root of your server's files, next to gamesave.zip.
3. Set Save Name to the file name without .zip, then restart.
4. Make sure the server runs the same Factorio version as the save, or a newer one. A newer build loads an older save, but an older build can't load a newer one. How to Update a Factorio Server and Pin a Version covers matching versions.

If your world uses mods, copy the host's mods/ folder across as well. Include Space Age if the save uses it: the expansion is itself a set of mods, so every player needs it too. How to Install Factorio Mods on a Dedicated Server covers the details, including the in-game mod sync that saves your friends hunting for zips.

Factorio Server Saves and Autosaves explains autosave slots and how to take a safe copy before you switch.

When Friends Can't Connect

Work through these in order. The first one is the usual cause.

• Version mismatch. The server and every client need the same build. If one friend is on Steam's experimental branch and the server is on stable, that friend can't join. Everyone switches branch, or the server is reinstalled onto the matching version.
• Mod mismatch. Factorio compares mod checksums on join and lists what's different. Accept the sync offer, or install exactly what the server runs.
• Wrong port. Players typed 34197 out of habit. Use the port from the Network tab.
• Wrong password. The panel field is the one that counts. See step 1 above.
• Hosting from home, friends time out. UDP 34197 isn't forwarded on the host's router. Switch to a Steam invite or a dedicated server.
• Server stuck before Hosting game at. It's still loading. A large map takes a while, and nobody can connect until that line appears.

Common Questions

Does every player need to own Factorio?

Yes. Every player needs their own copy. The headless server itself is free to run and doesn't use anyone's licence.

How many players can join?

The wiki gives a hard limit of 65,535 and notes that the practical limit is far lower. A GameServerKings server allows 50.

Can we keep playing when the host is offline?

Not when hosting from a player's game. The world exists only while that game is open. That is the main reason groups move to a dedicated server.

Do we lose progress moving from a hosted game to a server?

No. The save file carries everything: map, research, inventories and blueprints stored in the world. Upload it and set Save Name to match.

What to Read Next

• How to Set Up a Factorio Dedicated Server — the first boot, public listing and startup fields
• Factorio server-settings.json: Every Setting Explained — auto-pause, visibility and which keys the panel overwrites
• How to Install Factorio Mods on a Dedicated Server — getting a modded world onto the server
• Factorio Console Commands: Complete List & Cheats — admins, kicks and bans

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