The S500 TP Link electrical switch and the L535 light bulb will not join the TP Link extender without extraordinary manipulation. Although the extender offers these devises a much better connection, they always connect to the weaker router signal than the stronger extender signal. The these devices can be forced to join the extender only by shutting down the router while leaving the extender up and running, then the router can be restarted. The extender has a "perfect" connection to the router through EasyMesh.