How to make a gmod server run 24/7?

Just leave it on TBH and restart it like every day. Hosting services are the best.

You need to buy some server hosting dude if you tryna keep it up 24/7

you must buy some VDS or game server becuse you can setup your own pc but this is not healty for your pc and for server
if you want can setup your server
you can pm to me
and if you want you can buy game servers site and configed thet and you can play for this server
I recommand that vds beucse you can setup all games in it but this is not easy for normal users
I can help you if you want pm to me

Open the server and set the computer to sleep mode.

you need to set up your server on some hosting !

use game hosting servers like cridentnetwork or nitrous network, itlljust cause you a few bucks

Either buy a host, have your Server host PC turned on all the time or buy a dedicated server pc

Find a dedicated host! depending on the size if your server, it may only cost a few dollars a month up to 20 and 30 dollars a month. What game mode you are trying to host also makes a difference!

Buy a host, you can get a gmod host for a very cheap rate

You find a server host and tell them to put your server up 24/7.