EA9866

Cause

RADIUS server certificate validation failure

Fix Steps

1. Forget the WiFi network on your device
2. Access router admin panel at 192.168.1.1 or 192.168.0.1
3. Navigate to Wireless Security settings
4. Verify password contains no special characters that may conflict
5. Temporarily switch from WPA3 to WPA2/WPA3 mixed mode
6. Check MAC filter list and add your device if enabled

Related Errors

• T8558 – Actiontec T8558 Authentication Error
• MR3071 – Synology MR3071 Authentication Error
• RT-AX88U-E547 – Asus RT-AX88U-E547 Authentication Error
• C-3720 – Cisco C-3720 Authentication Error