Automation switch Rasp over AVR NEt IO board

Hi,
I have the Home Assistant running on my Raspberry 3.
I also have an AVR Net IO board installed where my garden light is connected to. So I can switch on my garden ligth manually over Home Assistant perfectly. Now I tried an autoamtion to switch on the lights automatically when the sun sets (including time offset and timer). The automation itself is working fine but sometimes the light is switched on and on some days teh light is not on (however the automation works…). I don’t know why…no idea?
Can anyone give me an advice?

switch:
  - platform: command_line
    scan_interval: 5
    switches:
      gartenlicht:
        friendly_name: Gartenlicht
        command_on: 'echo setport 6.1 | nc 192.168.xxx.xx 50290 && echo setport 6.0 | nc 192.168.xxx.xx 50290'
        command_off: 'echo setport 6.1 | nc 192.168.xxx.xx 50290 && echo setport 6.0 | nc 192.168.xxx.xx 50290'
automation:
  - alias: Gartenlicht an vor Sonnenuntergang
    initial_state: True
    hide_entity: False
    trigger:
      platform: sun
      event: sunset
      offset: "-00:15:00"
    action:
      service: homeassistant.turn_on
      entity_id: script.timed_gartenlichtabend
script:
 timed_gartenlichtabend:
    alias: Gartenlicht an mit Timer abends
    sequence:
      - service: switch.turn_on
        data:
           entity_id: switch.gartenlicht
      - service: script.turn_on
        data:
          entity_id: script.timerabend_off
  timerabend_off:
    alias: Timer Gartenlicht am Abend aus nach Zeit 5 h 30 min
    sequence:
      - delay:
          hours: 5
          minutes: 30
          seconds: 00
      - service: switch.turn_off
        data:
          entity_id: switch.gartenlicht