arduino nano appearing as usb 2.0 serial device

We have found uninstalling the third-party drivers to be a solution. This potentially leads to the mysterious port disappearance issue. So, if you have followed an upgrade path from an older version of the OS without native FTDI support to a new version that has it, there can be contention between the native and third-party drivers. Somewhere around the release of macOS 10.12 Sierra (and maybe earlier), native support for FTDI drivers was included. Earlier versions of Mac OS X did not support FTDI drivers, so users would have to install third-party FTDI drivers. The exact cause of this problem is not certain, but it seems to be related to Apple’s support, or lack thereof, for FTDI drivers in the operating system. Since we’ve seen this issue pop up internally and with many customers, we decided to share what solution has been working for us so far. Rebooting the system can temporarily restore the port, but the problem eventually comes back.

The symptoms we have observed generally include the spontaneous loss of the USB serial port connection to the board or loss of the port after disconnecting and then reconnecting the board from the USB programming cable.

Since our boards use an FTDI chip for USB-to-serial communication, we have witnessed some of these issues when working with our boards using Mac and macOS. Ongoing macOS FTDI driver issues plague many users connecting the Arduino IDE to boards that use an FTDI chip. How to Fix FTDI Driver Issue on Mac and macOS

Arduino nano appearing as usb 2.0 serial device