You can stop an existing instance by typing: Where user and instance are the name of the users you want to add to the instance. after that, you can start and stop them from the command line. One of the easiest ways to run multiple gmod instances on the same server is to add them as users to your user account. Once you have configured the server you can configure the other gmod commands (for information on how to specify a port number, see the instructions for gmod commands under the next section). if it isn't, go through the troubleshooting process. If you run through the commands above the gmod server should be running.