Regarding what happens with internet problems with VNC solutions, I just tried some software to use as a VNC to my computer and learned a few things.
If you use Port Map, use a mapping where the public and private ports are the same. This may decrease overall network security but is the surefire way for the solution to work. I tried making the mappings different. After I setup the VNC solution, I restarted the AP Extreme via AP Utility. When I did, once Port Map updated, it used the same private and public port but kept the 'desired private port' so any connections would not work to either port. When I turned off my DSL modem, Port Map updated correctly and things worked fine.
So the lesson is use the same public and private port number and you should be fine. When using the same port, the solution worked whether the Extreme was restarted or simply lost its network connection.
At the time of this test, I signed up for a free account with dnsalias.com. You can use their free service and download software to install. Once you do that you don't need to have the application open for it to update its service as a daemon runs in the background to update their service when a change in IP address is detected. I've found that Port Map must be running for it to work correctly. When I close it, the mapping no longer works.
As an example, I tried to open up the 5902 port but told it to use a different public port. When I did this, I tried out the setup by restarting the AP Extreme. When I did this the mapping came back different and it didn't work. is if I
