I have an HP 2450 connected in the same way, printing from windows and linux. I set up mine this way.
Using cups admin i.e. Open a browser URL is localhost:631/.
Add printer, or modify printer if already added - follow the prompts.
At the Device section; Device - AppSocket/HP Jet Direct
go to the next prompt and enter the URI to the printer.
Device URI - socket://192.168.x.x:9100
192.168.x.x is the address of my print server - naturally you should use the IP of your print server/port.
9100 is the Jet Direct port, it needs to be open on your firewall, if you have one.
Port 631 needs to be open for printing with cups.
Try the Jet Direct setup above and see how you go.