No serial port for my Nano

I recently bought a Nano. If I connect it to my MacBook there is no valid USB-port available in the IDE.
If I connect my Uno there are no problems, and I will see port /dev/cu.usbmodem1411 pop up.

I tried some other USB cables to see if it might be a load-only cable giving the problem, but switching cables makes no difference.

Could my Nano be damaged, or is there another problem?

Make sure the USB cable is completely plugged into both the Arduino board and the PC.

Which USB to TTL serial adapter chip does your Nano use? It is the largest black chip on the bottom of the board. It should say either "CH340G" or "FTDI" on top of the chip.

I plugged the cable in both sides.

The chip is not marked, I bought an open source clone.

If the chip is really not marked, you bought crap.

However, nowadays the text is laser engraved and barely readable. Take a photo in broad daylight and enlarge it on the PC and see if you can decipher it.

The chip is not marked, I bought an open source clone.

You probably need to install the CH340 drivers.

If that doesn't work, maybe try contacting the people who took your money.