Discovered that the hidden forums can still be accessed publicly if the link is known. Looking into possibility of having board names and info shown, but no posts accessible unless a user is logged in.
The boards are visible, but the latest post next to that board now has a note of: “Only registered and logged in users can see private forum boards.” Clicking on the board name will redirect the users to the login page.
This way potential new users can see what other boards are available, but cannot go into them or see the posts. Doing it this way will also help our Google and search engine rating, as they will pick up what subjects are available on the site.
Note: On most forums you can see where there is a board for the moderators and admin but no one without the right permissions can get in. That is now how this forum works. Logged-in users can see them, but will not be able to enter them unless they are a Moderator or an Admin.