I have not used this feature but I'll bet the printer won't show up automatically. You probably have to add the printer manually and then create a printer port manually. In the diagram below you can see I have a printer port set up for my old HP 5P printer (in my case I have a REALLY old SMC Barricade wired router being used as a print server). Click the add port button, choose standard TCP/IP and put in the IP of your router. I think you'll choose RAW/9100 but I'm not certain. If that doesn't work use LPR and you'll need to find out in the docs the name of the print queue.