Smart thermostat app reports 'Boiler Offline' or 'Device Offline'; thermostat appears normal but cannot control boiler.

Safety first: If the gateway is mains‑powered, switch off at the socket before unplugging cables.

• Check gateway LEDs: Inspect the Worcester Bosch internet gateway or smart controller. Confirm power, network, and status LEDs are lit as per the manual.
• Restart gateway: Power off the gateway for 30 seconds, then power back on. Wait several minutes for it to reconnect.
• Check network cable/Wi‑Fi: If using Ethernet, ensure the cable is firmly plugged into both the router and gateway. If using Wi‑Fi, verify the SSID and password are still valid and that the router is broadcasting.
• Check app status: Log out and back into the app. Check if Worcester Bosch reports any service outages on their support site.
• If still offline: The gateway or receiver may have failed. Contact Worcester Bosch support for replacement options.