I've had the same problem with both a Canon and a Brother MFC-8500. Both worked fine when connected to my new(ish) Mac. However, when I plug it in to the DNS-323, no printers are seen, by which I mean, on the device status page of the DNS-323, it doesn't list a printer:
PRINTER INFO :
Manufacturer: None
Product: None
Since this is a tertiary use of this little box (backups and media serving being the most important), I haven't put a lot of effort into it. I have, however, put in more effort than I should have to. If this wasn't well tested, it shouldn't have been included in the feature list. Truth is, I probably wouldn't miss it, but since it's there, I figure I have a right to use it as advertised.