If you have a ODG Power-Hub-System you can connect USB peripherals to the glasses via the Power Hub's USB Standard A Receptacle port. This includes hubs with embedded Ethernet ports and singular USB to Ethernet adapters.
We know that this hub works, for example: http://www.amazon.com/SY-HUB50045-Combo-Internal-External-100Base-T/dp/B008IKK0J0
(though it is very old and probably not available except on eBay) but, any powered USB hub will work with a separate USB to ethernet dongle, so long as the dongle uses the Asix AX88760 chipset. The older Apple USB/ethernet adapters works well, for example.
Once all the hardware is connected,on KitKat R-7s, go to System Settings -> Ethernet, or on Marshmallow R-7s, go to System Settings -> More -> Ethernet, and turn it on, and then select the eth0 interface, and then configure it for DHCP or Static.
If no eth0 interface shows up, the R-7 is not seeing the adapter; either the adapter does not have an Asix AX88760 compatible chip set, or there's an issue with your mag to mag cable or the Power Hub itself. To debug that, try connecting a simple USB mouse, and verify it causes a mouse cursor to appear and move around on the display. This would indicate the dongle is not supported.