ATS server_config.sii Explained: Every Convoy Server Setting

Q: Where is serverconfig.sii for the ATS dedicated server?

In the server's home folder: Documents\American Truck Simulator on Windows and ~/.local/share/American Truck Simulator on Linux. It is created the first time the server runs.

Q: How do I add a password to my ATS convoy server?

Set password: "yourpassword" in serverconfig.sii with the server stopped, then start it. Drivers enter it when joining.

Q: How do I make someone a moderator?

Add their SteamID64 to moderatorlist as a numbered line and raise the count to match, then restart. They become moderator automatically when they join.

server_config.sii is the one settings file for an American Truck Simulator Convoy dedicated server. It sits in the server's home folder (Documents\American Truck Simulator on Windows, ~/.local/share/American Truck Simulator on Linux) and controls the lobby name and password, player and AI traffic limits, ports, the Steam logon token, collision and speed rules, and the moderator list. Edit it with the server stopped, keep the format exactly as it is, and start the server again.

The server writes a fresh copy the first time it runs. Below is that file key by key, with the defaults from SCS Software's dedicated server documentation.

The file format

SiiNunit
{
server_config : _nameless.54e.4440 {
 lobby_name: "Desert Haulers"
 description: ""
 welcome_message: ""
 password: ""
 max_players: 8
 ...
 moderator_list: 0
}

}

A few rules that save you a broken server:

Text values go in straight double quotes. True and false are lowercase with no quotes.
Do not touch the server_config : _nameless... line or the braces.
Edit with a plain text editor. Word processors and some phone apps swap in curly quotes, which the server cannot read.
Changes load on the next start, not live.

Session identity

Key	Default	What it does
`lobby_name`	server name	Name in the Convoy session browser, up to 63 characters
`description`	empty	Second line in the browser, up to 63 characters. Good for "Weekly convoy Fri 8pm ET"
`welcome_message`	empty	Shown to drivers when they join, up to 127 characters
`password`	empty	Session password, up to 63 characters. Empty means anyone who can find it can join
`friends_only`	`false`	Limits who can see and join the session
`show_server`	`true`	Whether the session appears in the public browser. Hidden sessions are joined by search ID

Players and AI traffic

Key	Default	What it does
`max_players`	`8`	Drivers in the session. SCS documents 8 as the limit
`max_vehicles_total`	`100`	Cap on AI vehicles across the whole session
`max_ai_vehicles_player`	`50`	AI vehicles around each driver
`max_ai_vehicles_player_spawn`	`50`	AI vehicles that can be spawned per driver
`traffic`	`true`	AI traffic on or off

The AI limits are the main lever on how busy the roads feel and how much the server has to keep in sync. A full 8 driver convoy spread across the map means up to 8 separate pockets of traffic. If drivers report traffic popping in and out, the total cap is usually the reason, but raising it costs server memory and bandwidth.

On max_players: groups have raised it above 8 since update 1.50, but it is unsupported, and every driver then needs g_max_convoy_size in their own config.cfg set at least as high, or they cannot find the session. Our fix guide for ATS convoy servers you cannot join covers that and the other join problems.

A truck on the road in American Truck Simulator

Ports and the logon token

Key	Default	What it does
`connection_virtual_port`	`100`	Steam networking port, range 100 to 200. Not forwarded
`query_virtual_port`	`101`	Steam networking port, range 100 to 200. Not forwarded
`connection_dedicated_port`	`27015`	Game port. Forward TCP and UDP on a home server
`query_dedicated_port`	`27016`	Query port. Forward TCP and UDP. LAN discovery expects 27015 to 27020
`server_logon_token`	empty	Steam game server token. Keeps the search ID the same across restarts

Without a token, the server logs into Steam anonymously and gets a new search ID every start. Generate one at steamcommunity.com/dev/managegameservers using the ATS app ID 270880, which needs a Steam account that owns the game.

Driving rules

Key	Default	What it does
`player_damage`	`true`	Drivers can damage each other's trucks. Turn off for relaxed groups and new drivers
`hide_colliding`	`true`	After a teleport (ferry, job start, respawn), vehicles that would overlap another are hidden until they separate
`hide_in_company`	`false`	Hides other drivers inside company areas, so docks do not jam
`service_no_collision`	`false`	No collisions at service stations and truck stops
`in_menu_ghosting`	`false`	A driver in the pause menu becomes a ghost others drive through
`force_speed_limiter`	`false`	Forces the speed limiter on for everyone
`name_tags`	`true`	Shows driver names above trucks
`timezones`	`0`	Time zone handling, values 0 to 2
`mods_optioning`	`false`	Lets drivers join with or without mods their authors marked optional

Two common setups:

Friends who want to relax:

 player_damage: false
 hide_in_company: true
 service_no_collision: true
 in_menu_ghosting: true

Nobody gets rammed at a fuel pump and a friend who pauses to take a call does not cause a pileup.

A virtual trucking company convoy:

 player_damage: true
 force_speed_limiter: true
 name_tags: true

Real consequences and legal speeds, which is what most company events want.

Moderators and in session commands

moderator_list promotes Steam accounts to moderator automatically when they join. It is a count followed by one numbered line per SteamID64 (the 17 digit number, starting with 7656):

 moderator_list: 2
 moderator_list[0]: 76561198000000001
 moderator_list[1]: 76561198000000002

The count must match the number of lines below it. Moderators can use these chat commands in the session:

Command	Effect
`/set_time 06:30`	Sets the in game time, useful for a daylight convoy start
`/set_rain_factor 0`	Sets rain from 0 (dry) to 1 (heavy)
`/help`	Lists the commands available

That is the extent of the built in tools. There is no RCON for the ATS server.

Launch options that point at different files

The server can load a different config or packages file with -server_cfg "filename" and -server "filename". Groups that run a weekday base game session and a weekend DLC event keep two sets of files this way. -homedir "path" moves the whole home folder on Windows; on Linux, the XDG_DATA_HOME environment variable does the same job.

American Truck Simulator scenery

Editing it on a GamezServers server

On a GamezServers American Truck Simulator server, server_config.sii is in .local/share/American Truck Simulator/ in the file manager. The panel fills in four keys each time the server starts: lobby_name from the Lobby name setting, the two dedicated ports, and server_logon_token, which we create for you so the search ID never changes. Leave those four alone in the file and edit everything else (password, description, damage, traffic, moderators) there. Stop the server, edit, start it, and watch the live console for [MP] Session running. Exporting the DLC and mod packages that go next to it is covered in the ATS convoy server setup guide.

FAQ

Where is server_config.sii for the ATS dedicated server?

In the server's home folder: Documents\American Truck Simulator on Windows and ~/.local/share/American Truck Simulator on Linux. It is created the first time the server runs.

How do I add a password to my ATS convoy server?

Set password: "yourpassword" in server_config.sii with the server stopped, then start it. Drivers enter it when joining.

How do I make someone a moderator?

Add their SteamID64 to moderator_list as a numbered line and raise the count to match, then restart. They become moderator automatically when they join.

Why did my server stop starting after I edited the file?

Usually a missing quote, curly quotes from a word processor, or a moderator_list count that does not match its lines. Compare against a fresh default file.