Zyxel USG FLEX H Series [HA] - Firmware Update in High Availability (HA) Mode

In HA mode, the primary and secondary devices operate as a cluster. The update must be performed in a way that ensures proper synchronization and uninterrupted service.

Always back up the configuration:
Even if everything appears to work properly, always back up both devices before updating.

Firmware access:
– Use Cloud Firmware Upgrade directly from the device interface if available.
– For manual update, firmware files must currently be requested from Zyxel Technical Support.
 

Option 1: Cloud Firmware Upgrade

1. Access the active device via its web interface (through the management IP address).
2. Navigate to Maintenance > Firmware Management.
3. Click Cloud Firmware Upgrade, click Check Now, and if a new version is available, click Upgrade.
4. The device will download the firmware from Zyxel's cloud servers and install it. After rebooting, the secondary (passive) device will automatically synchronise and update, followed by its own reboot.
   

Option 2: Manual Firmware Upload via Zyxel Download Library

Manual firmware upload is supported — however, the firmware file for H-series devices (such as USG FLEX 500H) is not available for direct download via myZyxel or the public Download Library.

To obtain the firmware package for manual installation, you must:

1. Contact Zyxel Technical Support and request the required firmware version.
2. Once provided, access the active device's web interface and go to:
   Maintenance > File Manager > Firmware Management > Upload firmware manually.
3. Upload the received .bin firmware file and select Reboot and Activate.
4. After the active device restarts, the secondary device will automatically update and reboot, as long as HA synchronization is functioning correctly.

⚠️ This is a temporary limitation. Zyxel has announced plans to simplify firmware distribution for H-series in future releases.

Once you click the Upload button, the update process will proceed automatically. You can monitor the progress by observing status changes in the interface.

Upon completion of the firmware upgrade — typically within 10 to 15 minutes — navigate to the HA status section to confirm that both devices have been updated and that synchronization has been successfully re-established.

During the first 10 minutes after the update begins, Device 1 may initially display a status indicating no connectivity issues with Device 2.

However, after some time, the status will update to reflect the actual HA state. You can also verify this change by reviewing the system logs for detailed synchronization and connection information.