I would just like to report for the benefit of other members that, after considerable trouble, I managed to make the dns-323 work as a print server for my old but still excellent Canon MP800 printer (of course only for the printing side of this multifunctional), thus enabling four users in our home to print from their desks. The step was taken only when an extra print-server that I owned before acquiring the NAS suddenly died on us.
I should have checked this forum *before* starting, because the attempt to follow the regular Add Printer route resulted in data being written to the hard disk in the NAS that then had to be removed by reformatting the hard disks, as suggested by Fordem as a last resort, in reply to a similar question elsewhere on this forum.
So, having reformatted the hard disks on the DNS-323, I followed fordem's steps 6 steps (actually 7 steps, if you add the line on top about first deleting the printer from the computer) and was successful.
Thank you so much!