Ethernet not working after installing Security Update 2020-002 10.14.6 Mac OS X showed that a new update was available on my MacBook Air (2019) which I connect to the internet with using a USB-C to ethernet connector. [ I don't use wi-fi at all for health reasons.] After installing the update, my Mac no longer recognises the ethernet connection - the connection does not show up on the switch. I purchased a new USB-C to ethernet adaptor, and it too does not work ... from which I have figured out that the problem appears to be Apple's update. I am running Mac OS Mojave 10.14.6.

Any suggestions as to how to get my MacBook Air running again with ethernet ... is it possible to just install a new (or old or backup version of) the ethernet driver? If so, does anyone know which file to switch. Many thanks
As follow up to this very frustrating problem ...


On further analysis, the problem is that ONE of the USB-C ports stopped working (for both ethernet adaptors, and also for standalone USB to USB-C adaptors). The other USB-C port remained working fine.
After shifting the power input to the 'dead' port, that appears to have reset it, and it is now working again. I am suprised that this helped when re-starting the computer etc made no difference.