ATS Mods: Install Them and Run Them on a Convoy Server

Most ATS mods guides stop once the mod shows up in your own game. The harder part comes when you want the same trucks, trailers and map tweaks on a shared server, so everyone in your Convoy drives the same modded American Truck Simulator.

This guide covers American Truck Simulator mods from that angle: installing them on your PC, which kinds of ATS mods work in multiplayer, and how to move your mod list onto a GameServerKings ATS dedicated server. You don't upload a single mod file to the server. Everything goes through two exported files. If you only play single-player, the first section is all you need. The ETS2 version of this guide covers the same Convoy workflow for Euro Truck Simulator 2.

Installing ATS mods on your own PC

ATS reads mods from two places:

• Steam Workshop. Subscribe on the game's Workshop page and Steam downloads the mod. Workshop mods also update themselves when the author uploads a new version.
• Manual mods from other sites. These are .scs or .zip files, which go in Documents\American Truck Simulator\mod on Windows or ~/.local/share/American Truck Simulator/mod on Linux. If an archive unpacks into loose .sii files, you've unpacked too far. The mod is the .scs/.zip itself. You also have to update these yourself.

Then open the Mod Manager from the title screen and activate the mods you want for that profile. Mods are enabled per profile, so a Convoy profile can have a different list from your single-player one.

Which ATS mods work in Convoy

SCS added mod support to Convoy in update 1.42, but not every mod behaves the same way with other players:

A good rule for a shared server is to keep the required list short, prefer Workshop mods, and let personal visual mods be optional.

Putting your mod list on a GSK ATS server

SCS's own documentation explains why you don't upload mods: "Dedicated server does not require any additional DLC or mod data… As the dedicated server does not use the Steam Client, it cannot access the workshop." The server reads server_packages.sii (map, DLC lists, mod_list) and server_packages.dat (map data). You generate both in your own game.

On your PC:

1. Make sure your game is on the public release (1.61 at the time of writing), not a beta branch. GSK's ATS server updates itself on every restart while Auto update is 1.
2. In Documents\American Truck Simulator\config.cfg, set uset g_console "1" and uset g_developer "1".
3. Start ATS, load the profile with exactly the mods the server should require, and drive into the world. The map has to be loaded.
4. Press ~ and run export_server_packages.
5. The two files appear in Documents\American Truck Simulator\. Open the .sii and check that mod_list shows the number you expect.

In the GSK panel:

1. Stop the server.
2. In Files, open .local/share/American Truck Simulator/. It sits next to server_config.sii.
3. Upload both files, replacing the existing pair. Use SFTP if the browser upload struggles.
4. Start the server and wait for [MP] Session running. in the console.

The files GSK installs by default are a vanilla pair from December 2022 with mod_list: 0. We haven't confirmed that a pair that old still loads on the current game version, so export and upload your own pair even for an unmodded server. Reinstalling doesn't overwrite your upload, because the install script only fetches the defaults when the files are missing.

Allowing optional mods

Out of the box every exported mod is mandatory. To let drivers join with or without mods their authors flagged as mp_mod_optional: true, edit .local/share/American Truck Simulator/server_config.sii:

mods_optioning: true

Drivers also have to enable optional-mod servers in their session browser filter. Map mods ignore the flag.

Don't edit these four lines in the same file, because the panel rewrites them on every boot: connection_dedicated_port, query_dedicated_port, server_logon_token, lobby_name. Change the name and token in the Startup tab under Lobby name and Steam Auth token instead. Everything else in the file, such as password, max_players (8 at most), traffic and moderator_list, stays as you set it.

What your drivers see

When a driver tries to join a server whose mods they don't have, the game shows the missing-mods window: their mods on the left, the server's on the right. Workshop mods can be subscribed to from the in-game Steam overlay. Mods from other sites have to be downloaded manually, and the game can't tell whether they have the same version you exported with. So post a mod list with exact download links in your group's Discord. Once everything matches, Confirm lets them in.

Before your group's first modded run, have everyone back up their profile. SCS warned when Convoy mod support launched that modded sessions could, in rare cases, corrupt profile saves.

After an ATS update

Game updates are the usual reason a modded ATS server stops working for everyone at once. Restart the server so it updates, wait for your mods to be updated, check they activate in your own Mod Manager, then export and upload a fresh pair. SCS doesn't say whether packages exported on an older version keep working, so don't rely on the old pair. Take a backup first so you can restore the last working files.

If the server doesn't appear in the browser at all, the cause is usually ports or the Steam token rather than mods. See Players Can't Connect to My Server. The server's own log is server.log.txt in the same folder, with server.crash.txt after a crash.

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