Router crashes while trying to copy files to NAS (DD-WRT)

Hey guys, got a small issue.

I have a NETGEAR R6300 running DD-WRT v24-sp2 (09/27/13) kongac

I setup everything and it runs great except when I try to FTP files or copy files via UNC path. The router simply dies and restarts. It copies for a good few seconds then crashes. Anyone have any ideas? Do I have an outdated build?

Any advise would be great!