Smart thermostat shows E01 and cannot connect to the Internet; app reports device offline.

Safety first: This fault is low-voltage and generally safe to troubleshoot. Do not open the Internet Bridge housing. Only handle external cables and power supplies.

• Check bridge LEDs: On the Tado Internet Bridge, verify that the power LED is solid and the cloud/connection LED is on or blinking. If all LEDs are off, unplug the USB power and plug it back in using a known-good USB power adapter.
• Verify Ethernet connection: Ensure the Ethernet cable is firmly clicked into both the Internet Bridge and a working LAN port on your router. Try a different LAN port and, if possible, a different Ethernet cable.
• Confirm router Internet access: Check that other devices on the same router have Internet access. If the router is offline, reboot it and wait 5–10 minutes.
• Check DHCP settings: In your router’s admin page, ensure DHCP is enabled so the Internet Bridge can obtain an IP address. Avoid MAC filtering or firewall rules that could block the bridge.
• Reboot sequence: Power off the router for 30 seconds, then power it back on. After the router is fully up, disconnect the Internet Bridge USB power for 10 seconds and reconnect it.
• App verification: Open the Tado app and check if the bridge and thermostat show as online. If not, remove and re-add the Internet Bridge in the app following Tado’s pairing instructions.