LibRE requires all switches controlling a single zone to be connected to the port that contains the L2-DM in the socket. If you have wired for ReNetA, which supports any wiring configuration for 3-way switches, this adapter can combine the switch signals from multiple wires into a single port so the switches can easily achieve 3-way and more, and the drivers for the other ports can power their lights. See the back of the adapter for the wiring explanation.