You can add command args “-server Port=8000” to launch project:
In our project, we use command to launch dedicate server in Windows
E:\UnrealEngine\Engine\Binaries\Win64\UE4Editor.exe path_to_our_project_dir\xxx.uproject /Game/Maps/SomeMapsName Port=8000 -server
The specified port value maybe not real used.
In single System, you can run mutil instance of dedicate server;
The specified port value is a start value, if 8000 not valid, it will try to use 8001, and so on.