hass-config-example.yaml

# Example configuration.yaml entry
switch:
  # template switch that combines the mqtt switch and a binary sensor
  - platform: template
    switches:
      computer:
        friendly_name: "Computer"
        value_template: "{{ is_state('binary_sensor.computer', 'on') }}"
        turn_on:
          service: switch.turn_on
          data:
            entity_id: switch.computer_wol_proxy
        turn_off: # can also add your own turn off service here
          service: system_log.write
          data:
            message: "Computer does not support turning off"
            level: warning

  # MQTT switch that controls WOL-proxy
  - platform: mqtt
    name: "Computer-WOL-proxy"
    command_topic: "WOL-proxy/command"
    availability_topic: "WOL-proxy/status"
    payload_on: "ab-cd-ef-01-23-45"
    # payload_off: "OFF" # this does nothing
    payload_available: "Online"
    payload_not_available: "Offline"
    optimistic: true
    qos: 0
    retain: false

binary_sensor:
  # sensor that pings the computer to determine if it is on or off
  - platform: ping
    name: "Computer"
    host: [IP address of computer]
    count: 3
    scan_interval: 15