VNC connection woes ... maybe since Mavericks install

Used to have no trouble using vnc://<IPaddress> to connect to my father-in-laws iMac to help him work certain things out. Since I installed Mavericks I kept getting couldn't connect issues so I had him update too but that didn't help.

Remote Management is checked and green

Remote Login is checked and green too

I try using the actual IP address as well as his #######.att.net identity. The IP address times out after a while. The att.net identity errors immediately as if there is a syntax error. It simply says that either check my network connection or the screen sharing is not turned on....however, the screen sharing is controlled by the remote managment preference. I even tried hitting advanced to allow a connection to anyone who asks and assigning a password with no luck.

This should be as easy as before. What am I doing wrong or what has changed in Mavericks that I haven't checked?