replaced the router today with another RT-AC66UMy first thought is a hardware issue. I really can't think of anything firmware wise that would take down a single port with 'no lights'.
I would
- try re-plugging both ends of the cable and inspect the corresponding sockets for any problems
- try replacing the ethernet cable
- power cycle the pc
- power down the router, remove the power cable, then cycle the power switch a few times, replug the power cable and power up (discharges capacitors)
This one seems to have a little bit les range as the previous one (same 28E2 firmware)
maybee it needs to break in the wifi
opened up the old one.
i think the HN36201CG(decoupling transformer) might be damaged because it reads different ohms on the input.
desoldered it and gonna buy a new one from aliexpress.
hopefully i can repair the port so i have a spare router