A direct connection may not be the way you want to run the DNS-323, but it would have served my purpose, the key to diagnosing a problem is to simplify - to remove all but the necessary items - had you done that you would have known whether you should be focusing your investigation on the network or on the end point.
I'm not going to stick around where I'm not wanted, so I'll leave you to your debate, but before I go, there's something I want to show you ...
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As you can see, the DNS-323 is capable of disk reads exceeding 27Mbyte/sec (roughly 250 mbit/sec) & writes in excess of 17Mbyte/sec (150 mbit/sec) - obviously you'll need to be running a gigabit network to achieve this sort of performance, and Memnon, this was done with a 32bit system at the other end.
When I say the DNS-323 is unlikely to be the cause of your speed issues, I'm 99% serious.
Oh - the details of the image can be found
here.