Most people shouldn't have to port forward (feel sorry for the Airport users out there). The new system we are using instead of the direct port>port is called UPnP (universal plug and play). I won't go into details on what this means, but basically, your router does the hard work for you when a program utilities this feature.
Most routers have this feature, however it seems a large majority of these come with it defaulted as OFF. So you will need to enable it, you can do this via the web interface of your router normally and just look for the "UPnP settings" or something.
If your router does not support UPnP you can always port forward.
TL;DR
If your friends can join your server - You need to change nothing
If you can't join their server - They need to enable UPnP
(Could be other causes however this is most likely)
Servers may show as "---" after they are shut down, this is how the server list works, it will not instantly get rid of a server when it can't contact it (as far as I know).