Occasional Contributor

DSL-2780 - QoS Setup - how to prioritize a device / IP address?

I'm stuck in the D-Link DSL-2780 QoS menu - I want to prioritize one device which is connected to my router and has a fixed IP address, but the "IP QoS" page in the Advanced->Network Tools section of the router menu leaves me nowhere to specify my device IP address. What am I doing wrong here?