I got exactly the same one, the Cable matters plug, initially I tested it wth my usb 2.0 dongle which failed (as in my post above) then I got the usb 3.0 dongle and it works like a charm! you can also connect via wifi for the other tv features to continue to work as well. This a massive fix for the TV!
How can usb ethernet be used for streaming and wifi for the rest?
gigabit ethernet on smart TV
in LG webOS Smart TV Questions
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How can usb ethernet be used for streaming and wifi for the rest?