E6 error appears and thermostat cannot connect to Wi‑Fi or Kasa app

Note: This error affects app connectivity but usually not basic heating/cooling control.

• Power cycle: Turn off the HVAC breaker for 60 seconds, then restore power. Wait for the thermostat to fully boot and check if E6 clears.
• Router check: Ensure your router’s 2.4 GHz band is enabled and the SSID is broadcasting. Kasa thermostats typically do not support 5 GHz only networks.
• Distance and interference: If the thermostat is far from the router or near metal ducts, electrical panels, or large appliances, consider relocating the router or adding a Wi‑Fi extender.
• Forget and re-add: In the Kasa app, remove the thermostat device, then perform the pairing process again following the in-app instructions.
• Firmware update: If you can briefly connect, update the thermostat firmware from the Kasa app.
• If E6 persists: The Wi‑Fi module or antenna on the main PCB is likely defective. Replace the thermostat.