LAN party server setup: network, game servers and downloads

For a LAN party you want every machine on one wired switch, one dedicated server box (or a hosted server, if the venue's internet is decent) running the games you plan to play, and every game installed and updated before anyone arrives. Local servers give the lowest latency and survive the venue's internet failing; hosted servers save you carrying hardware and keep running after the party. Most modern games still need internet to authenticate players even on a LAN, so "LAN" rarely means "offline". Below: the network, the server box, LAN mode game by game, download caching so forty people do not all pull the same 80 GB update, and the failures that eat the first two hours of every LAN.

Local server or hosted server#

The first decision is where the servers run. Both work; they fail differently.

A local box wins for competitive shooters, where a millisecond matters to people, and for venues with poor or unreliable internet. A hosted server wins for persistent games the group will carry on playing after the weekend - the Minecraft world or Valheim save that becomes the group's server - and for small events where carrying another PC is a nuisance.

Plenty of LANs do both: a local box for the tournament games and a hosted server for the co-op world. Game traffic is small - a few hundred kilobits per second per player for most titles - so a venue with a reasonable connection handles a hosted server for thirty people without strain. What it does not handle is thirty people downloading updates at the same time, which is a separate problem with its own fix further down.

The network#

Most LAN party problems are network problems, and almost all of them disappear with cables.

Wire everything. Wi-Fi at a LAN party is thirty devices plus thirty phones competing for the same channels in one room. Latency spikes and packet loss follow. Use gigabit Ethernet to every gaming machine and the server, and keep Wi-Fi for phones.

One flat network. A gigabit switch (or several, linked) with everything on the same subnet. If you need more ports than one switch has, connect switches together rather than daisy-chaining through someone's PC. Unmanaged switches are fine at this scale.

One DHCP server. The venue's router usually hands out addresses. If you bring your own router, make sure only one device on the network is doing DHCP - two will hand out conflicting addresses and machines will drop off at random.

A fixed address for the server box. Give it a static IP or a DHCP reservation, so the address you write on the whiteboard at 18:00 is still right at 02:00.

Size the uplink honestly. If the venue's connection is shared with other people, ask what it is. A 100 Mbit/s line is fine for gaming and miserable for updates. Game server bandwidth per player gives typical figures by game, and latency, jitter and packet loss helps you tell which problem you have when someone complains of lag.

The server box#

A spare desktop makes a perfectly good LAN server. Requirements are modest: a recent quad-core with high single-core speed, 16 GB of memory to run three or four servers at once, an SSD, and a wired connection. It does not need a graphics card beyond whatever lets you see the desktop.

Set it up at home, a week before:

1. Install the operating system and all updates. Windows works for nearly every game; Linux is lighter and runs most of them natively. Linux vs Windows game servers covers which games need which.
2. Install SteamCMD and every server you plan to run. SteamCMD explained has the commands; game server requirements by game the memory each needs.
3. Configure each server, start it, and join it from another machine on your home network.
4. Write a start script or shortcut for each server so that on the day, starting a game is a double-click.
5. On Windows, allow each server through the firewall on private networks, and make sure the venue network will be treated as private. A network marked public blocks inbound connections by default, and this is the single most common "nobody can see my server" at a LAN.

Then, the day before, run every server once more to pull any updates. Updates released overnight will still catch you, which is why local download caching matters.

LAN mode, game by game#

"LAN mode" means different things in different games. Some genuinely play offline; most still authenticate every player online and merely skip the public server list.

Source games: TF2, CS:S, Garry's Mod, L4D2

sv_lan 1 in server.cfg makes the server LAN-only: it is not listed on Steam's master server, and only clients on the local subnet can join. Players find it under the LAN tab of the server browser, which discovers servers by broadcast on the local network. Players still need Steam running and logged in. For a mixed event where some people join from outside the venue, leave sv_lan 0. SRCDS basics covers the rest of the configuration.

Counter-Strike 2

CS2 servers for LAN tournaments are run with sv_lan 1 as well, with players connecting by connect <ip> in the console. Steam has to be online for players to launch the game at all, so a total internet outage stops CS2 regardless of where the server is. CS2 competitive match server config has the match settings.

Minecraft

A dedicated Java server with online-mode=true authenticates every player with Microsoft, so it needs internet. With online-mode=false it does not - which also means anyone on the network can join with any name, including an admin's. At a private LAN where everyone is known that is an acceptable trade if the internet is unreliable; anywhere else it is not. "Open to LAN" from a single-player world is the zero-setup alternative for a handful of players, though it runs the world on one person's PC. Minecraft server.properties explained covers online-mode and the rest.

Others

The older a game, the more likely it plays truly offline - which is part of why classic games stay popular at LANs. For anything modern, assume the internet must be up for players to sign in, and treat a local server as a latency improvement, not as insurance against an outage.

Downloads: the problem that eats the first two hours#

Thirty people arrive, start Steam, and every one of them has a 20 GB update for the game you planned to start with. On a 100 Mbit/s connection that is many hours. This is the most predictable failure at any LAN, and it has three fixes, best used together.

Tell everyone to update before they come. The day before, post the game list and ask everyone to launch each game once at home. Half will.

Run a download cache. LANCache (from the lancache.net project) is a caching proxy that runs in Docker on a box at the venue. The venue's DNS (or the cache's own DNS service) points Steam, Battle.net, Epic and other content hosts at the cache; the first person to download an update pulls it from the internet, everyone after gets it from the LAN at local disk speed. It needs a machine with a large, fast disk and a wired connection, and some set-up of the DNS on the network. For an event of more than about fifteen people it is worth it.

Use Steam's local transfer. Steam can copy game files from another PC on the same network instead of downloading them, if the setting allowing transfers from local network devices is enabled. It helps, but only when someone on the LAN already has the exact version.

Power, heat and the physical side#

The unglamorous part decides whether the server is still up at three in the morning.

Count the watts. A gaming PC under load draws a few hundred watts, a monitor another thirty to fifty. Twenty setups on one domestic circuit will trip a breaker, usually at the moment a match goes to overtime. Ask the venue how the sockets are split across circuits and spread the tables accordingly. Put the server box and the switch on a circuit with as few gaming PCs as possible, and ideally on a small UPS, so a tripped breaker elsewhere does not take every game down with it.

Keep the server out of reach. A server box under a busy table gets kicked, unplugged to charge a phone and covered in coats. Put it, the switch and the cache box together somewhere visible but out of the walkways, with labelled cables.

Mind the heat. A room full of PCs gets warm quickly, and a server box shoved against a wall with its fans blocked will throttle. Leave it room to breathe.

Bring spares. A few spare Ethernet cables of different lengths, a spare power strip and a small spare switch cost little and fix most of the hardware problems that turn up on the day.

Running the event#

Write the server list on a whiteboard. Game, IP and port, password if any. Most questions at a LAN are "what's the address?".

Start servers when you need them. Each running server costs memory and CPU on the box. Run the current game and the next one, not all eight.

Give servers and maps time. Big Workshop collections and custom maps take time to load the first time. Start the server for the next game ten minutes before the current one ends.

Have a plan for the internet failing. A list of games that work offline, already installed and tested, saves the evening.

Keep the persistent world. If the group played on a co-op world, copy the save before you pack up - or play it on a hosted server from the start, so it is still there next week. Running a modded server for friends covers keeping it going after the event.

Troubleshooting on the day#

Nobody can see the server. On Windows, the network is probably marked public and the firewall is blocking inbound traffic. Change the profile to private or add explicit firewall rules for the server's ports. Then check that the server and players are on the same subnet.

Some players see it, others do not. Two DHCP servers, or some machines on Wi-Fi on a different subnet from the wired ones. Check the IP addresses: everyone should share the first three numbers on a typical home-style network.

Lag spikes for everyone. A machine on the network is saturating it - usually a download. Check whether the cache is working, and whether someone is streaming in high quality over the same uplink.

"Connection failed: Steam not logged in". The internet dropped, or the player's Steam is in offline mode. Most modern games cannot authenticate without it.

The server box itself is slow. Too many servers running at once. Stop the ones nobody is playing.

FAQ#

Do I need a dedicated server at a LAN party?

Not always. Many games let one player host from inside the game, which is fine for small groups. A dedicated server is better for more than about eight players, for competitive games and for anything you want to keep running when the host's PC is being used for something else.

Can we play without internet at a LAN party?

Only games that support offline LAN play. Most modern titles need online authentication even when the server is on the same network. Older games and some indie titles work fully offline - check each game you plan before relying on it.

Is a hosted server too laggy for a LAN?

For co-op and casual play, no: 10-40 ms is unnoticeable in most games. For competitive shooters at a tournament, a local server's sub-millisecond latency is noticeably better, and players will notice the difference.

How many game servers can one PC run?

A modern quad-core with 16 GB comfortably runs three or four small servers at once - a CS2 server, a TF2 server, a Minecraft server and something light. Memory is usually the limit; check each game's needs.

What is LANCache and do I need it?

It is a caching proxy for game downloads. It stores every update the first time anyone downloads it and serves later copies from the local network. For more than about fifteen people, it saves hours of waiting.