Ubuntu 18 HPLIP cannot detect printer Laser 100 series

Hello.
Just got printer HP Laser 100 series, configured it with a Windows PC, was able to print via Wi-Fi, and was also able to print with smartphone device via Wi-Fi
I followed the instructions in https://developers.hp.com/hp-linux-imaging-and-printing/gethplip to install hplip, and now can pop up the client by typing hp-setup.
In the "HP Device Manager - setup" when i select "Network/Ethernet/Wireless network (direct connection or JetDirect)" i get the following error message:

"
HPLIP cannot detect printers in your network. This may be due to existing firewall settings blocking the required ports.
                When you are in a trusted network environment, you may open the ports for network services like mdns and slp in the firewall. For detailed steps follow the link.
                 http://hplipopensource.com/node/375 "

Link doesn't seem to work. I also tried selecting "Show Advanced Options"->"Manual Discovery" and typing in the IP Adress of the printer but obtained the same error.

Any ideas on how to fix?