Garry's Mod Server Configuration: Startup Flags and server.cfg

Garry's Mod Guide • Updated Sep 1, 2026

Garry's Mod Server Configuration

GMod configuration has two layers: startup parameters decide how the server boots, while garrysmod/cfg/server.cfg applies persistent console variables. Keeping those layers separate makes “it works in the console but not after restart” failures much easier to diagnose.

Last verified: September 1, 2026. Facepunch's command-line reference warns that sv_lan must be set before startup or followed by a changelevel. A value added only to server.cfg can be too late for initial server behavior.

Recommended startup baseline

./srcds_run -game garrysmod -console \
  +maxplayers 16 \
  +gamemode sandbox \
  +map gm_construct \
  -port 27015

Add one change at a time. Workshop collections, a GSLT, and a custom gamemode should be tested after a stock map boots.

Useful startup flags

Flag	Purpose	When to use it
`-game garrysmod`	Loads the GMod game directory.	Every GMod dedicated-server launch.
`+map MAP`	Chooses the first map.	Use a stock map for troubleshooting.
`+gamemode MODE`	Selects the gamemode.	Set it before testing gamemode-specific addons.
`+maxplayers N`	Sets player slots.	Start small; size for Lua/addon load, not a generic maximum.
`+host_workshop_collection ID`	Fetches a public/unlisted Workshop collection.	After vanilla setup passes; see the Workshop guide.
`-noaddons` / `-noworkshop`	Disables addon or Workshop loading.	Isolation tests for startup and join failures.
`+sv_lan 1`	Starts as LAN-only.	Set at startup for LAN testing, not only in server.cfg.

Keep server.cfg small and explicit

Create garrysmod/cfg/server.cfg with only settings you have verified for your gamemode:

hostname "My GMod Server"
sv_lan 0
sv_password ""
sv_cheats 0
sv_contact "admin@example.com"
// Keep RCON credentials out of public repositories and chat.

Use the Facepunch command reference for a variable's current behavior. Unknown, obsolete, or gamemode-specific cvars can be silently ignored or produce misleading diagnostics.

Passwords, RCON, and operator safety

sv_password controls player access; leave it empty for a public server.
Use a separate strong RCON secret, restrict access to trusted administrators, and rotate it if exposed.
Publish truthful server name, gamemode, map, and rules. Facepunch's operator rules require accurate server information and prohibit malicious actions toward players.

Map and gamemode changes

Use changelevel MAP after changing a setting that needs a new map, including the documented sv_lan timing case. Keep a known-good map and gamemode pair in the startup script so a bad Workshop item cannot leave the server without a boot path.

Configuration troubleshooting

If a setting disappears after restart, confirm it belongs in server.cfg rather than the startup command.
If LAN/browser behavior is wrong, set sv_lan before launch or changelevel, then retest.
If the stock map works but the custom stack fails, restart with -noaddons and -noworkshop.
If players join but see missing content, use the Workshop download guide; config alone cannot fix an absent delivery path.

Related Garry's Mod guides

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Garry's Mod Server Configuration: Startup Flags and server.cfg