- sensor:
    - name: router_uptime
      state: >-
        {% set uptime = states.sensor.simstrup_gateway_uptime.state | int %}
        {% set days = (uptime / 86400) | int %}
        {%- if days > 0 -%}
          {{ days }} days, {{ (uptime - (days * 86400)) | int | timestamp_custom('%H:%M:%S', false) }}
        {%- else -%}
          {{ uptime | int | timestamp_custom('%H:%M:%S', false) }}
        {%- endif -%}