You’re right in saying that these devices are basically ancient, and also right about why you should never use all-in-ones for anything that you would want to last more than a couple of years.
http://support.dlink.com.au/download/download.aspx?product=DNS-320 The age of the devices:
Firmware: 1.00
Hardware: A1
Date: 2010/9/7
First DNS-320 firmware release
Can you explain further, or give an example?