vnc viewer behind router won't connect

[Fred Rubble]

I'm trying to connect to another server which isn't using a firewall
or a router from my home computer (viewer) which is behind a router
(over the internet, but not using the web interface).  I can't receive
a connection or even get to the password screen.

I've read various posts that all relate to setting up port connections
to get past the server firewall or router but I'm not sure if the
issue is that I'm connecting from a viewer behind a router.

Thanks for any help!