First of all, you should understand, that it is one of tplinks best-seller, so I suggest to think about problem from your side firstly. I bet it is a cable problem. I would change patch-cord, if it is possible. Do you have any error on your network connection on PC? No link maybe or unkown connection? The only problem, which could be with switch, is hardware problem, so you should just go to service-center/shop.