Your solution which relays on "share port" utility works OK.
Till now I was not using the share port utility. The printer was available as network printer on path \\<dns323 name>\lp. Once I upgraded DNS 323 to firmware 1.10 the printer is still visible on that path but it just ignores all print jobs. I sent an E-mail to support - no answer.
The "share port" solution is a different approach which I just found out now from your reply.
The disadvantage is that on (each) PC I need to install and run the share port client. Also before a print job was queued by DNS 323 if the printer was off and printed when printer was turned on; with share port the printer must be on when a print job is submitted.
The advantage is a superior connection with the printer (now I can see the fax as well, I can see printer status and cancel jobs etc.).
It seems that "share port" solution is the only one which works with 1.10 firmware.
DLink support should publish SharePort 3.1 (latest working version) on DNS 323 page as well. I hope someone from DLink reads the topics here...
Thanks for your elegant solution, I can use again my printer.