Walli charger displays E17; app shows 'OCPP server error' or 'Backend communication fault' on connected models.

Safety first: This is a network issue; it does not directly affect electrical safety.

Steps:

• Check local network: Verify that the site router and internet connection are working by testing another device on the same network.
• Verify OCPP settings: In the Walli app or installer portal, confirm the OCPP server URL, port, and credentials are correct.
• Time and date: Ensure the Walli charger's time and date are correct (via NTP or manual setting), as TLS connections can fail with incorrect time.
• Reboot charger and router: Power cycle both the Walli charger and the network router.
• If E17 persists: Contact the backend provider to confirm server status. If other chargers connect fine, the Walli communication module may be defective and require replacement.