The Vaillant app on a smartphone cannot connect to the vSMART system while on the same Wi‑Fi network; remote access may still work or vice versa.

Steps to restore app connectivity:

• Disable VPN: Turn off any VPN or private DNS services on your smartphone and retry the connection.
• Same network check: Ensure the phone is on the same LAN (not guest Wi‑Fi) as the vSMART gateway.
• Router firewall: Temporarily relax strict firewall settings or enable UPnP/multicast if disabled, then test the app.
• Update app and firmware: Install the latest version of the Vaillant app and ensure the gateway firmware is up to date.

If the app still cannot connect locally but remote access works, the issue is likely with router configuration rather than the vSMART hardware.