Smart thermostat shows E11 and cannot pair with the Internet Bridge during installation.

Safety first: No electrical risk; only handle low-voltage devices.

• Update app: Ensure you are using the latest version of the Tado app on your smartphone.
• Check device codes: Carefully re-enter the serial number and authentication code printed on the thermostat and Internet Bridge. Avoid mixing similar characters (e.g., O and 0).
• Single home association: Confirm the Internet Bridge is not already registered to another Tado account. If it is second-hand, request the previous owner to remove it from their account or contact Tado support.
• Reduce interference: Place the thermostat within 1–2 meters of the Internet Bridge during pairing and keep other RF devices (e.g., DECT phones, Wi-Fi routers) a bit further away temporarily.
• Restart both devices: Power-cycle the Internet Bridge and remove/reinsert the thermostat batteries, then retry pairing.