vSMART thermostat or app shows incorrect time or a 'Time sync' / 'Clock error' message, causing schedules to run at wrong times.

Steps to correct time issues:

• Check internet stability: Ensure the vSMART gateway has a stable internet connection. If the device frequently goes offline, fix Wi‑Fi or router issues first.
• Verify time zone: In the Vaillant app, open system settings and confirm the correct country and time zone are selected. Adjust if necessary and save.
• Router settings: Log into your router and ensure that outbound NTP (UDP port 123) or general time synchronization is not blocked by firewall rules or parental controls.
• Firmware update: Check for firmware updates in the app and apply them. Many time sync issues are resolved by software updates.
• Manual time set (if available): If the app allows manual time setting as a fallback, set the correct time and monitor if it drifts again.

If the time continues to drift or cannot sync despite a good internet connection, the vSMART gateway may have an internal clock or firmware fault and may need replacement.