First, set up your router/modem and make sure it is connected to the internet.
Bridge X
If your network credentials have changed, you’ll need to do a Wi-Fi reset on your Bridge X. Hold down the WPS button for 5 seconds. The Wi-Fi LEDs will light up once the Bridge has reconnected to the Wi-Fi.
Heat Pump Optimizer X
If your network credentials have changed, you’ll need to reconfigure the Wi-Fi connection on your Heat Pump Optimizer X, then reinstall it in the tado° app in Settings > Rooms & Devices > Add device.