I recently recieved a new Macbook Pro. This was one of the latest 2016 models, that have the touchbar. Mine took a little longer to ship as I got it maxed out. When i arrived I went through the standard setup proceedure for a new mac. I then attempted to hook up a USB-C Ethernet Adaptor from C2G. It was suppose to work right out of the box, but it didn't work. I hooked the same device into another collegue of mines new Macbook Pro 2016 and it worked. I could see the Network panel load a device by the name of "AX88179 USB 3.0 to Gigabit Ethernet". So I went looking on the internet, thinking if I could find the driver and install it on my mac, I could get it work. I found the USB-C driver here: http://www.asix.com.tw/FrootAttach/driver/AX88179_178A_Macintosh_10.6_to_10.12_Driver_Installer_v2.8.0_20161108.zip
For those that are scratching your head trying to figure out why your USB-C Ethernet adapter is not working maybe that could help. It did for me.