I bought several Arduino nano cards shipped from China and, when I plugged it on my Mac, the serial USB port disappear (dev/cu.usbmodem.1411). I thought they are bad quality. I bought new one on eBay from France but the problem is exactly the same: Arduino software doesn't recognise the card. It works well with several Arduino Uno boards.
Can you help me to find what's wrong?
Many thanks, Virgil