If you have a USB-to-RS485 version of the UCOM 208-2, you MUST install a driver. If it has a DB9 connector only, it uses your PC’s built-in COM port (no driver needed).
Good news: Most Linux kernels include native drivers for CH340 and PL2303. ucom 208-2 driver
Prolific has deliberately disabled older chips on newer Windows versions. If you have an old PL2303HX chip, Windows 10/11 will show "PL2303HXA PHASED OUT SINCE 2012" error. If you have a USB-to-RS485 version of the