here's my problem, I want to be able to remote control my grandparents computer in order to help them without having to drive 20 minutes to get there. however I can only connect to their machine when I'm on the same network. I'm using the default vnc server vino with vinagre client.what settings do I have to use to make it work? (their os 10.04.4 , mine is 11.10)
The problem with VNC is that in most cases you have at least one firewall between your destination computer and your machine. That's why you are unable to connect unless you are on the same network.
ISPs used to put firewalls on their ends in some cases (eg. mobile internet) but if you use a router to share the internet connection between multiple machines (or just to make it easier to connect) you need to traverse through its firewall.
In an ideal case you have the following setup:
In this case (and assuming the ISPs put no restrictions on the connection) you only need to know the Remote PCs IP address.
But usually this is the setup:
Now (still assuming the ISPs do not restrict your connection attempts) the Remoter Router's firewall will block you unless you do a port forward on it to the destination machine.
So depending on the remote router you need to create a port forward rule and forward TCP/5900 to the destination PCs TCP/5900 port.