Thermostat displays F4 and may disable remote access or advanced smart features while basic temperature control still works.

Safety first: No electrical work is required for this fault; do not open the thermostat.

• Check internet connection: Confirm that other devices on the same network have internet access. If not, resolve the ISP or router issue first.
• Verify app login: Log out and back into the Payne thermostat app. Ensure your account is active and the thermostat is still listed.
• Re‑pair thermostat: In the app, remove the thermostat device, then follow the on‑screen instructions to add it again, scanning any QR code or entering the thermostat ID.
• Check router firewall: Ensure your router is not blocking outbound connections for the thermostat. Disable overly aggressive firewall or parental control settings temporarily to test.
• Wait for service restoration: If Payne has a known cloud outage (check their support site), F4 may clear automatically once service is restored.
• Factory reset as last resort: If all else fails, perform a factory reset on the thermostat and set it up again from scratch.