Whenever I try to register to play multiplayer, I get an error saying the CD-key isn't registered to my account, "Well duh, that's what I'm trying to do." So to my question, how do I fix this?

This site lists currently active multiplayer servers. Using the Client Extension Rhiyo linked above, you can browse this list in-game and connect to them.

http://www.nwnlist.com/

You'll need to paste the CD-Keys from your GOG account into the nwncdkey INI file located in the game installation directory to resolve the "no cdkeys registered to your account" issue.

The Client Extension, as listed above, re-enables the integrated multiplayer server browser (which can be used to find and join PWs, etc.). Pasting in your CD-Keys is a prerequisite for being able to play online.

Are you still able to use direct connect?

Yes. Just type in any username/password, and after your login authentication fails you'll still be able to proceed and use the direct connect option.

Make sure you use the same username whenever you log in or you won't be able to access your server vault characters.

The link is dead. I can not find the patch anywhere else. any ideas

A live link to the latest version of the Client Extension can be found here:
http://neverwintervault.org/project/nwn2/other/nwn2-client-extension

Hey yall I'm having a issue with getting onto a multiplayer server I know it works have a friend on there as we speak. It keeps popping a error saying my cd key is unatherized how do I fix this please help