Impossible problem? Galaxy S20 5G "malfunctioned" error when connecting to PC.

[the real webgrunt]

Just got a refurb SM-G981v Galaxy S20 5G phone from Amazon.
Connected it to my computer (not a laptop) to access folders as this is the way I prefer to add custom ringtones. I made sure USB settings on the phone are set to allow data transfer. Computer says "USB device not recognized - The last USB device you connected to this computer malfunctioned, and Windows does not recognize it." The phone does start charging when the cable gets connected to the PC.
Tried reinstalling the Samsung USB driver, same problem.
Tried a different cable and a different USB port. Same problem.
Connected my Galaxy S7 to the computer. It came right up and I was able to browse the files. So my USB port and computer seem to be working fine. Must be a problem with the phone?
But when I connected the S20 to my laptop to test it, it and it came right up and I was able to browse files. So the phone and cable seem to be fine....on the laptop.

So I ruled out the computer as a problem, ruled out the cable and phone as a problem, there's nothing left. Everything checks out--but the computer still says the phone malfunctioned and won't talk to it.

Edit: It gets weirder. I installed DeX and Kies. They can't see the phone. But the Windows app Phone Link can, it can even run apps on the phone!

 

[Laura Knotek]

What version of Windows are you using? Have you tried a different USB port on the PC? What type of USB port is it, type 3.2, 3.0, or 2.0?

 

[the real webgrunt]

What version of Windows are you using? Have you tried a different USB port on the PC? What type of USB port is it, type 3.2, 3.0, or 2.0?

It's Windows 10. USB 3.1 ports. I did mention I tried a different USB port. However I see your line of thinking and agree. There's something about my setup on this system that is preventing it from recognizing the phone. I don't think it's the USB port itself because first, my laptop is older and is able to see the phone and second, the Phone Link software can access the phone just fine on this PC. I think it's some sort of driver or OS issue but the laptop has the same version of Windows.

 

[Laura Knotek]

It's Windows 10. USB 3.1 ports. I did mention I tried a different USB port. However I see your line of thinking and agree. There's something about my setup on this system that is preventing it from recognizing the phone. I don't think it's the USB port itself because first, my laptop is older and is able to see the phone and second, the Phone Link software can access the phone just fine on this PC. I think it's some sort of driver or OS issue but the laptop has the same version of Windows.

Do you have the USB ports on the PC set to selective suspend? Maybe this would help. https://www.windowscentral.com/how-prevent-windows-10-turning-usb-devices

 

[the real webgrunt]

Do you have the USB ports on the PC set to selective suspend? Maybe this would help. https://www.windowscentral.com/how-prevent-windows-10-turning-usb-devices

I checked this, and selective suspend is set to disabled.