E9991

Cause

Pre-shared key mismatch between AP and client

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
7. Re-enter WiFi password carefully on your connecting device

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