Os detalhes do produto aqui parecem indicar que ele suportará unidades externas:
- File system support
Internal HDD: EXT4
External HDD: NTFS, EXT2, EXT3, FAT32, ReiserFS, XFS
Aqui está uma revisão com mais algumas pistas ...
- Other NAS backup strategies backup drives to externals as files when schduling "jobs". They are accessible from your computer using the external drives if the NAS fails. This box does scheduled jobs in a proprietary format, so you would have to by another Zyxel to restore. There ARE two ways around some of this: A: A setting for the front button will let you backup one of your shares and mirror it to an external drive. You cannot schedule this though. B: You can use drag-and-drop or software on your computer to cause files to move/mirror to an external drive as files. BUT, since you are passing through your CPU, it is slower and bound by that computer remaining on.
Honestamente, não parece que você vai querer perder tempo com isso ...