Firmware can be downloaded from our Zyxel website: https://www.zyxel.com
Download archived firmware from our FTP server: ftp://ftp.zyxel.com
Some service provider equipment use proprietary software/firmware designed specifically for/by the ISP. Please make sure you upload the correct firmware onto your device. Loading the incorrect firmware may cripple the device rendering it unusable. Please verify the firmware version currently installed on the appliance and load patches with same revision.
Example: A device running software/firmware version 5.11(ABCU.1)C0 may only run patches with "ABCU" revision. Software/Firmware version number may change, such as 5.12(ABCU.1)C0 or 5.11(ABCU.3)C0, but the revision will stay "ABCU".