Enabled guest to public forum read but forum read access is denied.

We enabled guests to public forum read but even members are not getting this error message below: 

Access denied. You must have special permissions to access this area or you are not logged in.

Please let us know how we can fix this issue. Thanks.

You need to make sure the forum topic/category is not set to Private.

How do we make the all the forum topic/posts public?

I am also trying to allow Guests to post comments in the Forum. I have not set anything to Private and a Guest is not able to post/comment.

Does anyone know how to allow this?

(I have done an extensive search for everything involving guests and found nothing)