Thousand player on Single map Dedicated server hardware and network requirements?

I wanna build open world. i mean thousand players same time on single map simultaneously.
Thousand player on Single map Dedicated server hardware and network requirements?
They can talk each other.

I am afraid that there is no simple solution to that, it all depends on the magnitude of your project, the number of systems and code you have in your project, depending on how many players are running that code if it is efficient or not, there are many variables, my recommendation would be that you try to put bots and go testing with various hardware, you can limit the connection with some software and continue testing.