Local Backup Options

With the demise of Crashplan for Drobo I’m looking in the short term for a local backup solution. I’d like the backup to be automated if possible. Here is a list of my hardware:
Large external USB 3 drive
Asus router with a USB 2 and 3 ports. The router supports hard drive connected USB Applications including FTP Share, Network Place (Samba) Share / Cloud. Third party firmware adds NFS sharing. There is also a disk spin down option.

Ideally there would be a Drobo app that can automatically backup to an FTP/SMB/NFS share (hanging off the router).

Please let me know your thoughts!