Custom C++ Server Collision Handling

I made a longer post with this but apparently it didn’t go through for some reason. I’m gonna summarize for now and add on later

Our game has a master server in C++ that tells the client which server instance to connect to. There can be anywhere from 1 to 100 server instances on a single machine.
The dedicated server is still 1-2GB (last i checked) and it’s just not practical to have multiple copies like that on a single machine.
The memory usage and such is also very high compared to a custom C++ server.

However, the only thing I’ve came across where someone has done this is here : - YouTube
He has multiple videos about it, but it’s the same person.
It doesn’t look like he handles any collision of any kind, and I was wondering how you would even go about doing that?

I know it’s a huge topic to discuss, but I was hoping someone out there had an answer/ideas/suggestion for me