Port Selection in Business Edition

[BillP]

We are trying to manage a single SC 1500 on a single server.
We lost communication with the APC some time ago without realizing it.

When we look at the Device Manager, we see the Prolific USB-to-Serial Bridge on COM4

However, when we go to:
Protected System and then under that, System Settings, on the Device Communication Port, There are only COM1, COM2 and COM3 as choices.

What do we do now? The server is in a remote location, and I can't access it directly.