Well, the last post on this subject was back in 2013. It's been about 4 years on this thread.
I the DNS-325 is nearing it's end of support days, but mine is still chugging along as a total champ!! I too have been limited with external backups in general. As far at via USB- my DNS325 has the option "USB to NAS", and "NAS to USB", as as scheduled event.
My problem is this:
I have a 2TB Western Digtal Caviar Black mounted in an USB 3.0 external drive enclosure. Three partitions. All three NTFS. The drive works fine when connected to my laptop, but when I connect to the NAS, I have three things happen. 1) The NAS chokes and hangs 2) the NAS reports it can see he USB, but only reports the presence and brand- no volume(s) and 3) doesn't see a USB at all.
Is there any hope you, anyone sees my problem and has a solution PLEASE contact me. I know... this thread is quite old. Chances are slim...