E19 displayed and thermostat cannot connect to Johnson Controls cloud or mobile app despite Wi‑Fi being connected.

Safety: No high‑voltage work is required, but avoid opening the thermostat unless necessary.

• Step 1 – Confirm internet access: Verify that other devices on the same Wi‑Fi network can access the internet.
• Step 2 – Check time and date: Ensure the thermostat’s time and date are correct, or enable automatic time sync if available.
• Step 3 – Router settings: Make sure your router is not blocking outbound connections required by Johnson Controls (check for firewall rules or parental controls). Reboot the router.
• Step 4 – Sign out/in: In the Johnson Controls app, remove the thermostat from your account, then re‑add it following the pairing instructions.
• Step 5 – Firmware update: If possible, update the thermostat firmware via USB, SD card, or local service tool as specified by Johnson Controls.
• Step 6 – Replace thermostat if persistent: If E19 persists and all network conditions are normal, the internal network stack or security chip may be faulty. Replace the thermostat.