Windows 11's driver signature enforcement.
Once in DFU mode, Windows 11 should theoretically detect the device. But in practice, you often need to manually intervene.
However, a common roadblock for developers, hobbyists, and engineers is getting the STM32 DFU driver to work correctly on . Microsoft’s latest operating system introduces stricter driver signing policies and a revamped USB stack, often causing "STM32 DFU" devices to show up as "Unknown Device" or fail to install automatically.
The most reliable way to get the is to use the official ST toolchain. STMicroelectronics provides a driver installer within their programming suite.
Loading a bootloader with DFU — Dev documentation - ArduPilot