Thank you for your question.
Have you tried to connect your LAN cable to other end device? If so did the end device had connection?
Have you tried using different cable? What were the results?
Do you get internet from TRB140 USB port?
This problem could've caused bad cable or end device not visible for some other reason (such as damaged network card).
You can also try to factory reset the device again, maybe factory reset was not fully completed.
Let me know if this helped you.