Shelly 2L Gen4 installs behind a double wall switch and keeps the existing wiring unchanged. Its two channels bring both connected lights under smart control without rewiring or wall work. When low-wattage lights are used, the included Shelly Bypass for 1L/2L* ensures stable operation. From there, both lighting lines can be scheduled, controlled, and automated in the Shelly Smart Control app while manual control from the switch remains fully available.