Some (many?) HDMI cables can also carry Ethernet over HDMI. The main use seems to be to provide internet connection to a smart TV from a cable modem box. Currently I have an ethernet-USB adaptor ...
Still running 10.14.6 on my ancient mid-2014 15" MBP. I don't have a spare TB-GbE adapter, but I do have two USB-GbE adapters based on the Asix AX88179 chipset. After a recent OS update semi-broke the ...