It sounds to me like he is testing a single device plugged into the ED and if so, signal reflection would not be much of an issue. If it were, it should also have some issues with the DMX dongle as well and he claims that it is working normally with the DMX dongle. It either a 4 port passive hub or a Pixelnet combiner is put in between them, that woul remove the multi-pair issue and ifot starts working then, that was th problem and if not, then there is an issue between the ED and the little DMX cotroller.