Out of the sudden only one LAN port on NAS 520 working

Dear all, 

In 2016 I had the issue with my Zyxel NAS 520, that only one of the two LAN ports worked.
I sent the devise for repair and on return the statement from Zyxel was, that a firmware update solved the issue. The device never showed this issue again.  A week ago I sold the NAS 520 and the buyer told me exactly the same error I had two years ago. Unfortunately the firmware is the latest one already... .

Do you have any ideas, on this? Maybe flash the same firmware again?

Thanks and best regards,

Nico.


#NAS_Aug_2019