With my phone (SGS4) I had problem with the phone connector, I ordered the micro USB to HDMI cable but the connection between phone and cable wasn't good, whenever I picked up the phone from table the connection was lost, so I've bought on ebay new "phone connector" for me it is http://www.ebay.com/itm/291639915722...%3AMEBIDX%3AIT
for 5$ and the cable works flawlessly. Maybe the problem can be also there, but I would start with resoldering the cable
Anyway, I resoldered the cable and bought a new usb-ethernet adapter, it looks like it works perfectly well now I am pleased, I really wanted it, it's like I have a second computer now. I wonder if some day the phone makers will be nice enough to add such a simple and useful possibility. But maybe too many people prefer wifi, unfortunately.