ZyXEL Communications ZyWALL 110 Handbook page 733

5 Make sure the version of the USB firmware is different from that of the running
partition. The device writes logs on the console and device log if the firmware
version is the same as the running firmware.
Console Message
MONITOR > Log > View log
6 This feature does not support the Device HA Pro firmware auto upgrade to
passive devices. Do not use USB firmware upgrade on devices with Device HA Pro
function activated. When using USB firmware upgrade on a device HA or in a
device HA Pro scenario, make sure you plug the USB storage to the passive
device for firmware upgrade first. After the passive device has finished firmware
upgrading through the USB, plug the USB storage to the active device for
firmware upgrade.
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