look, on server you have to run server.bat and on client you have to run client.bat, simple as that

in server.bat put multiplayer11.exe -sv -cl -port 2300
in client.bat put multiplayer11.exe -cl -ip localhost ---- that's for test on single pc
in client.bat put multiplayer11.exe -cl -ip "server's ip" ---- that's for internet test

i hope you understood me this time