Thermostat shows C002 and cannot reach the GLAS cloud service; local control works but mobile app and voice assistant integration fail.

Safety note: No high‑voltage work is required for this fault. Do not open the HVAC cabinet unless you are qualified.

• Step 1 – Verify internet access: Use a phone or laptop on the same Wi‑Fi network to confirm you can browse the web. If not, reboot modem and router and contact your ISP if needed.
• Step 2 – Check router firewall: Ensure outbound HTTPS (port 443) is allowed. Disable any strict firewall or security appliance temporarily to test.
• Step 3 – Confirm time and region: On the GLAS settings, verify the time zone and date are correct. Incorrect time can cause SSL certificate failures.
• Step 4 – Reboot GLAS: Remove the thermostat from the wall plate for 30 seconds, then reattach to force a full reboot and reconnection attempt.
• Step 5 – Update firmware: If local network works, check for a firmware update in the GLAS settings. Apply any available update and reboot again.
• Step 6 – Test on hotspot: Temporarily connect GLAS to a mobile phone hotspot. If cloud connection works on the hotspot but not your home network, the issue is with your router or ISP configuration.
• Step 7 – Hardware suspicion: If C002 persists across multiple networks and after firmware updates, the GLAS main board may have a network stack or TLS hardware fault, requiring thermostat replacement.