I had the same problem and must have spent 1-2 hours talking on the DLink help line with no success.
I finally returned the unit and within 2 minutes after testing it I was told that it was operating outside of the specifications and this defect was causing the problem.
I was given a choice of my money back or a replacement unit. I hesitantly accepted a replacement unit and it has operated with no problem other than a glitch with the SharePort print utility for which I have yet to find a fix.