Windows 10 refusing to install Drivers for Mega 2560 V3

I can use my Nano which is a clone oddly enough. But the Mega shows as an unidentified device in device manager.

When I try to manually install the driver it correctly sees it as an Arduino Mega 2560, but it says drivers not found.

I have let windows try to find its own drivers. I have pointed to the drivers folder and tried a manual install and I get the same result regardless.

I uninstalled Arduino IDE and reinstalled. Same result.

Bad board you say? Brought it the office and plugged it into my Win 10 machine and it worked flawlessly.

I’m out of ideas. Been messing with this all day.

Usual Q.

Clone or real deal ?
If clone what is it using for the USB chip ?
Do you have full privileges on the computer at home and is your very own personal computer ?
What security do you have on the machine that does not work ?
Which version of win 10 exactly ?

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Thanks for responding.

The chip is the Atmel ATMEGA2560, so real deal I assume.

It's my PC (built it myself) with full admin privileges. I even over rode device signing.

I'm not at home, so I can't tell you which version of Windows I am running, but I believe the last update it has was May 2019 if that's helpful.

I am back at the office and doubled checked again and it works splendidly here. Same cable just to be sure.

When it comes to drivers, the chip of interest is not the primary ATmega2560 microcontroller, but the USB to TTL serial adapter chip on the board. This is the largest black chip right behind the USB socket on the board. It will either say "MEGA16U2" or "CH340" on it.

From this description:

it correctly sees it as an Arduino Mega 2560

I am doubtful that it could be a CH340, since the Mega derivative boards that use the CH340 can't be identified by name by your computer.

I can confirm that it is an Atmel chip. I cannot read more even with a magnifier. I doubt it's a clone. In an case I have the CH340 drivers fully installed. My Nano clone works fine and show those drivers.

I am starting to think I have a Windows or Mobo issue with my home setup.