www.zyxel.com
Extract firmware zip file.
Upload the Firmware on the ZyWALL/USG
In the ZyWALL/USG, go to MAINTENANCE > File Manager > Firmware Package >
Upload File. Click the To upload image file in system space pull-down menu and
select (1) or (2). The default Standby system space is (2), so if you want to upload
new firmware to be the Running firmware, then select the Running system space
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