Bosch EasyControl shows error C6 and the thermostat cannot connect to the internet or Bosch cloud services.

Safety first: Network changes are low risk, but do not open the EasyControl casing.

• 1. Check local Wi‑Fi: Use a smartphone at the EasyControl location to verify that the home Wi‑Fi network is visible and has a strong signal (at least 2–3 bars).
• 2. Verify credentials: In the Bosch EasyControl app, re-enter the Wi‑Fi SSID and password carefully. Avoid special characters that may not be supported.
• 3. Router settings: Ensure the router’s 2.4 GHz band is enabled (EasyControl typically uses 2.4 GHz). Disable client isolation and ensure that outbound connections to Bosch cloud servers are not blocked by firewall rules.
• 4. Reboot network: Power cycle the router and any mesh nodes. After the network is stable, reboot the EasyControl by removing power for 30–60 seconds.
• 5. Test guest network: Temporarily connect the EasyControl to a simple guest network (no captive portal) to rule out complex security settings.

Professional help: If all network checks pass and other devices work fine but C6 persists, the EasyControl Wi‑Fi module may be defective and the unit may need replacement via Bosch support.