Digi One SP on COM2 possible?

I’m trying to configure the Digi One SP using RealPort to be on COM2 but the lowest com port is COM5 in the drop down box. The application that I need to run with the Digi One SP only supports up to COM4. My PC only has one com port and it’s set to COM1. How do I get the Digi One SP to run on COM2-COM4?

Tech support directed me here: