开云体育

Hi Bob,
I experienced the same, did loose com port after upgrading firmware to the latest 1.2.20 version. I dont know what went wrong but I also lost the dfu recognazion.
I managed to get it work again by reinstalling the DfuSe_Demo- v3.0.6_setup.exe with nanovna connected to PC.
Then I installed the firmware version 1.2.00 and the com port was there again and all work OK.
I hope the same works for you too.

73 Jouko OH5RM