I'm having the same issue and dare not even try another dlink print server.
I have 2 dlink print servers dp-301u previously connected to hp laserjet 2420 with no problems whatsoever,
I just changed the printers to hp laserjet p3005 and now, after like 30 minutes,
but it will not print until I unplug the usb cable and plug it back in. however, the printer is reportedly still in "Ready" mode when this happens. (its as though only the usb connection goes to sleep).
if I unplug the usb cable and plug it, and print a single page, it will go through.
immediately, from microsoft word, I print another page. although the printer server will report as "printing"
there is no response from the printer until i unplug the usb cable and replug it.
the hp laserjet p3005 has no issues with linksys psus4 print server (but no longer on sale)
I can find people with similar issues (search terms: dp-301u hp 3005) but no solution. is this a print server issue or a printer issue? I've already updated print server and printer firmware to latest, turned off sleep mode and sleep timers to 4hrs.