Thermostat displays C001 and cannot connect to Wi‑Fi network; cloud features and remote app control unavailable.

Safety first: This issue is low‑voltage and generally safe to troubleshoot with power on, but if you remove the thermostat from the wall or open the HVAC equipment, turn off power at the furnace/air‑handler breaker.

• Step 1 – Verify Wi‑Fi network: Confirm your router is broadcasting a 2.4 GHz network (GLAS does not use 5 GHz only). Check that the SSID is visible and that other devices can connect.
• Step 2 – Check distance and signal: Stand near the thermostat with a phone and check Wi‑Fi signal strength. If it is weak or drops, move the router closer, add a mesh node, or temporarily relocate the router to test.
• Step 3 – Re‑enter credentials: On the GLAS touchscreen, go to Settings > Network, forget the current network, then re‑select your Wi‑Fi and carefully re‑enter the password. Ensure the security type (WPA2, etc.) is supported by your router.
• Step 4 – Check router settings: Disable MAC address filtering, guest‑network isolation, or parental controls that might block new devices. Ensure DHCP is enabled and there are free IP addresses.
• Step 5 – Power cycle: Reboot the router and modem. Then remove the GLAS thermostat from its wall plate for 30 seconds and reattach to reboot the thermostat.
• Step 6 – Factory network reset (if needed): If C001 persists, perform a network reset from the GLAS settings menu and set up Wi‑Fi again.
• Step 7 – Suspect Wi‑Fi module failure: If multiple known‑good networks fail and other devices connect fine, the internal Wi‑Fi/Bluetooth module on the GLAS main control board may be defective. Replacement of the thermostat assembly is typically required.