When you change a setting for a tado° product using HomeKit (e.g. with the Apple Home App or Siri) it is treated as if it was a manual input on the tado° device. This means that your tado° switches to Manual Control.
HomeKit generally only allows you to access HomeKit-enabled devices from your iOS devices whilst you are connected to your home Wi-Fi network. To control a HomeKit device from somewhere else, an Apple TV, HomePod or iPad is required - you can learn more about this on the dedicated Apple HomeKit Website.
For more information about tado° and HomeKit refer to our HomeKit Section.