Thermostat shows E02 and cannot connect to Gosund cloud or mobile app, even though Wi-Fi signal is strong

Safety note: No high-voltage work is required for this fault. Do not open the thermostat unless instructed by support.

• Step 1 – Verify local Wi-Fi access:
  • Confirm the thermostat shows a strong Wi-Fi icon.
  • Use a phone on the same network to browse the internet; ensure connectivity is stable.
• Step 2 – Check router and firewall:
  • Disable any outbound firewall rules or parental controls that might block IoT devices.
  • Ensure DNS is set to a reliable provider (e.g., your ISP or a public DNS like 8.8.8.8).
• Step 3 – Sync time and update firmware:
  • In the Gosund app, check for a firmware update for the thermostat and apply it.
  • Ensure the thermostat’s time zone and time are correct (automatic time sync enabled).
• Step 4 – Relink device to Gosund account:
  • In the app, remove (delete) the thermostat from your account.
  • Factory reset the thermostat (usually Settings > Reset > Factory).
  • Re-add the thermostat in the Gosund app following the pairing instructions.
• When to escalate: If E02 persists across different networks (e.g., mobile hotspot) and after firmware update, the cloud client on the main PCB may be corrupted; contact Gosund support for replacement.