Dell Mobile USB-C DA300 to HDMI/VGA/Ethernet/USB 4K Adapter 

is more than just a USB Ethernet adapter.

Compatibility

Win7/8/8.1/10, MAC

Manufacturer Part# : 0YC7D
Dell Part# : 492-BCJF

NO LINUX SUPPORT LISTED.

https://www.dell.com/en-us/shop/dell-usb-c-mobile-adapter-da300/apd/470-acwn/pc-accessories

http://accessories.ap.dell.com/sna/productdetail.aspx?c=th&s=dhs&sku=492-BCJF

Additional Product Notes

1. Only one video output is supported at a time.
2. Available with select PC models (with support for DisplayPort Alt-Mode 1.3 & above standard) when connected to displays that offer 4K resolution at 60Hz. Otherwise, default resolution will be 4K at 30Hz.
3. a) When adapter is connected to a Thunderbolt or 15W USB-C (DisplayPort Alt-mode) port – two downstream USB-C and USB-A ports with USB3.1 Gen 2 file transfer rate of up to 10 Gbps is supported.
b) When adapter is connected to a 7.5W USB-C (DisplayPort Alt-mode) port – only one of the two downstream USB-C and USB-A ports with USB2.0. file transfer rate up to 480 Mbps is supported on a 1st come 1st serve basis

(the peripheral connected first to either the USB-C or USB-A port is supported)

4. USB mice, keyboards, mice dongles, select SSDs and flash drives.

5. Dell Business Class Features include:
PXE Boot – Pre eXecution Environment Boot allows a computer to be troubleshot remotely when connected to the network via its network card. Wake-On-LAN – Starts your PC remotely using the signal over your network. MAC address pass-through – MAC address pass through recognizes only a unique MAC address entered in the system’s BIOS (Basic Input/Output System) by overriding the adapter MAC address every time your laptop is connected to the network, ensuring that your PC’s MAC address stays the same no matter which USB-C adapter you use.

6. Tested with macOS High Sierra 10.13.4 and macOS Sierra 10.12.6

change power from auto to on.  works for me.

https://ask.fedoraproject.org/t/usb-c-dongle-dell-da200-ethernet-port-not-working/5406