I can't connect to x11vnc from different network

I am trying to connect from my laptop (with Linux Mint) to my remote desktop (with Linux Mint too) using VNC Viewer on my laptop and x11vnc on my desktop. I manage to connect if I am on the same network but if I try to connect to x11vnc from a different network, it doesn't work, staying stuck in "Connecting to 192.168.x.x" window. How could I solve? Thanks in advance!