How to change max players on a GMod server
Add +maxplayers 32 to the server's launch options for 32 player slots. It cannot be changed while a map is running.
maxplayers
Sets the number of player slots on the server; on a dedicated server set it at launch with +maxplayers.
maxplayers <count> Examples
+maxplayers 32 Launch command line form for 32 slots.
Arguments
countRequired- Number of player slots.
What it does
Defines how many players can be connected at once. On a dedicated server it is normally given on the launch command line, because it cannot be changed while a map is running.
The game's own description: Change the maximum number of players allowed on this server.
Good to know
sv_visiblemaxplayerschanges only the number shown in the browser.
Run it on your server
On a SLASHPLAY server, type it in the Console tab of the server page; the reply shows right under it. A value set there lasts until the server restarts. To keep it, add the line to garrysmod/cfg/server.cfg. New to this? Start a GMod server first.
Your own
GMod server.
From $0.03 an hour, only while it runs. New accounts get 6 free tokens.