The "PoE"[0] board was also a USB device wired onto the pins for the single USB port on the board. USB is not a multidrop bus - if you directly wire two devices to a single USB port it will not work, you need an active USB hub.
[0]quotes because looking at that FTDI chip though my bet is it's actually serial over Cat5...
[0]quotes because looking at that FTDI chip though my bet is it's actually serial over Cat5...