During setup, the Vaillant app cannot find the vSMART internet gateway or reports 'Gateway not found'.

Steps to complete setup:

• Confirm power and LEDs: Ensure the gateway is powered and its status LEDs are on. Refer to the manual for the LED pattern indicating pairing mode.
• Same network: Make sure your smartphone is connected to the same local network (SSID) as the gateway/router, not to a guest network or mobile data.
• Enable pairing mode: Press and hold the pairing or reset button on the gateway as described in the manual until the LED indicates pairing mode.
• Disable AP isolation: In router settings, turn off client/AP isolation or similar features that prevent devices from seeing each other on the LAN.
• Try Ethernet: If using Wi‑Fi, connect the gateway to the router via Ethernet cable and retry detection.

If the app still cannot find the gateway and the LEDs do not show normal operation, the gateway hardware may be faulty and require replacement.