Dear TP-Link Support Team,

I am reporting a critical issue with the Archer NX500 router regarding WAN failover behavior.

Device:

• Model: Archer NX500 (5G AX3000)
• Firmware: RG500LEUAAR07A01M4G_BETA250429_V01_P162

Configuration:

• Primary WAN: EWAN (PPPoE – Fiber)
• Backup WAN: Mobile Data (5G/LTE)

Issue description:

The failover mechanism works partially as expected:

• When the EWAN (fiber) connection fails, the router correctly switches to mobile data.

However, the failback mechanism is not working:

• When the fiber connection is restored, the router reconnects via PPPoE (status shows "connected"),
• BUT traffic continues to be routed through the mobile data connection.
• The router does not automatically switch back to EWAN.
• The only way to restore normal operation is to manually disable mobile data.

Impact:

• This causes unnecessary mobile data usage and additional costs.
• The router does not behave as expected for a primary/backup WAN setup.

Additional notes:

• This issue appears to affect multiple NX-series models (NX200, NX600) based on community reports.
• It seems related to routing priority or failback logic rather than link detection.

Expected behavior:

• Once EWAN is restored and stable, the router should automatically switch back to the primary WAN without manual intervention.

Request:

• Please confirm whether this is a known issue.
• Provide a firmware fix or workaround.
• Clarify whether automatic failback is officially supported on this model.

If needed, I can provide logs or additional diagnostics.

Thank you for your assistance.