Good Practice of testing a big multiplayer project

Hi there !
thanks for taking the time to read my post. I have been working on a project and it is like old days virtual world like project where different people join in and play games and interact with other players.
The thing is i wanted to know is there a way to test like 5 players at the same time without running 5 instances because i do not have access to like 5 computers and i tried using 2 unity instances to test for 2 players and that was already very performance heavy.
there are lots of games that have far bigger scope than my project thats why i wanted to know what are the industry standards in testing these types of projects.
Thanks once again!

In any case, you want to add a command line parameter that then has a code path that connects to your test server and does certain things like move around repeatedly, picking up/dropping items etc or whatever you can script in a certain way.
You can run your game’s EXE with -batchmode -nographics and it won’t render anything at all
You can add a command line parameter that when it sees, the code hides or disables many graphical elements, and reduce the visual quality including render distance. You could simply set the Camera’s far plane to be really close (like 1) - things like that.

You can make a VirtualBox VM image or docker image, running VirtualBox or Docker locally, with a Linux build of your game, so you can copy/paste it to all the VM machines or Docker at once in preparation
You can use online resources like Azure VMs using a web interface to easily spin up several VMs or Docker so you have multiple machines.
You should be able to run it multiple times with -nographics and be able to get at least a few copies of your game per machine.
These are just ideas.