you can also do a port scan for the IP address of the printer connected to your Wifi network. In my case the following ports are active.
Port 631 is used for Internet Printing Protocol. I assume this is what CUPS in my case uses to communicate and print.xxx.xxx.xxx.xxx : 80
xxx.xxx.xxx.xxx : 81
xxx.xxx.xxx.xxx : 82
xxx.xxx.xxx.xxx : 83
xxx.xxx.xxx.xxx : 443
xxx.xxx.xxx.xxx : 515
xxx.xxx.xxx.xxx : 631
For scanning PeasyScan also doesn't detect my HP, but I can scan by providing the IP address in a config file. Printing and scanning are working on different ports.