USB Serial Adapter COM Port Assignment Changes on Windows 10 Reboot

Question

I have a Windows 10 Pro laptop with a USB Serial Adapter with an attached printer. Every time I reboot, the COM Port assigned to the adapter changes. Sometimes it is COM3, other times COM4. When the COM port changes, the printer port assignment is wrong and the printer no longer works.

What can I do so the same COM port is always assigned to the USB Serial Adapter every time the computer reboots?

Answer 1

@Michael Schumann
Hi,
The Windows assign the COM port according VID, PID and serial number. So with the same device plug in, it should always get same COM port assignment. However, two devices with same VID, PID and serial number might be treated as same device.
Try setting the COM number manually in Device Manager:

1. Open Windows Device Manager > right click the device > Properties
2. Under Port tab > Advanced
3. Change COM port number

If the cable is connected to the same USB port, it should get the same COM number.
Hope above information can help you.

============================================

If the Answer is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.