How to protect / make private our Custom Pages?

We have a gated community. Everything requires people to log in to view contents, except our Custom Pages, that are (unwillingly) public.

This wasn't our intention, and we don't know how it all ended up this way.

We would like to make the Custom Pages private as well, so whenever someone tries to access them, they redirect to the login screen.

How can we do that?

Many thanks,