I suggest you contact Sonoff Support on the problem.

To see if a device connects to the router:

  1. Power off the Sonoff device (turn off switch, unplug from outlet, remove battery)
  2. Go to the router CLIENTS page and take screenshots of actively connected devices
  3. Power up the Sonoff device and wait until it boots and enough time to connect
  4. Go to the router CLIENTS page and compare with previous screenshots to see if there is a new device connected