What does the 'blocked by key handshake fail' log mean and how to resolve the issue?

Zyxel_Judy

The 'blocked by key handshake fail' log indicates that the authentication process between a device and the network has not been completed. This typically occurs due to the following reasons:

Poor signal strength

This can be verified by checking the event log.

Solution: It's recommended to adjust the deployment of your AP to ensure a stronger signal. Ideally, the client connection signal should be -70dBm or above for optimal performance.

Incorrect password

The device attempting to connect might be using the wrong password.

Solution: Confirm that the correct password is being used for the network connection. Check whether space/ specific characters in the password (Configure > Access points > SSID advanced settings)

Network interference

If there are interferences in your network environment, it might prevent a successful connection. In general, if your channel utilization is over 50%, you might start experiencing issues. Over 70% could lead to a poor WiFi experience, and over 90% utilization may render the WiFi virtually unusable. This can be confirmed by checking the AP's Channel Utilization under Device > Access Points.

Solution: Fine-tune your site configuration to prevent interference and improve network performance. You can go to Configure > Access points > Radio settings and do this by following the steps below:

• Select the Deployment selection based on your number of APs or adjust your 2.4GHz radio power to be 5dBm lower than your 5GHz radio.

• Change Channel setting:

Enable DCS

Disable the 'Avoid 5G DFS channel' setting to prevent channel interference.

Disable 'DCS client aware' to allow the AP to choose the better channel, even if clients are already connected to the AP.

• Increase your WLAN rate control to 5.5Mbps for 2.4GHz, and 12Mbps for 5GHz.
  
• Enable 'Broadcast Storm Control' and 'Multicast Storm Control' on both the AP and the switch port that the AP is connected to (AP part: Devices > Access points > click on the device > Device page > Status > Storm control)

By carefully monitoring and adjusting your network setup, you can ensure the best performance and connectivity for all connected devices.