Reinstalling After Effects might be the easiest fix for this as Cinema 4D Lite is bundled with it. You don't need to download the trial. Instead of trying to import a .C4D file can you add the Cineware effect to any layer and click the blue "Options" button next to the effect name? You'll get an error if you add the effect to a non-.c4d, but it's fine for this purpose.

It sounds like you already know how to get to this since you mentioned changing the port number, but what happens if you click the "Default" button?

If that still doesn't work (after restarting After Effects) then I would recommend reinstalling it from the CC app.