I have Intel NUC NUC5i5RYH and recently the network port stopped working. I use Debian Linux and had the device working for over a year with no issues. I did not install any updates before the network port stopped working. I've tried, new cables, different ports on router, a different router, and a loop back detector. The link lights on the network port do not light up no matter what I do. I've tried using the network boot feature in the Boot Selection screen at startup and am not able to detect link there either.
Does anyone have suggestions on if this can be fixed? Is this a hardware failure?
If the LEDs do not light up, it likely means the PHY IC has failed. Presuming you are stull under warranty, I suggest you contact Intel Customer Support directly and make arrangements to have the base unit replaced.