Midi port 4; where is it?

I’m using cubase artist 10.5 on windows 10.
Also, motif XF and the VST editor.
I think I need to activate midi-port 4,
But it doesn’t appear on the midi-port set up page.
Ports 1, 2, and 3 are visible and active, however.
Does anyone know where port 4 might be?