I'm looking for a Software for Mac OS X to backup my NAS (mounted via samba share) to an external hard drive connected to my iMac.

With Windows I used SyncBack SE (from 2BrightSparks Pte Ltd). But there is no more Windows now ...

Usually most backup software is designed to use a network device as a backup destination but struggle if you want to backup a network device to a local hard drive. For my local system backup I use Time Machine but I didn't found an option to backup my NAS with Time Machine, too.

Any suggestion is welcome