Cannot block wp-login.php

I set up the custom login address, and indeed Cerber creates this page and I’m able to log in there. However, I also clicked the option for it to block access to wp-login.php. This does not work. I can still access that page.

I was previously using other security plugins, and thought I had made a mess, so I tested on a fresh wordpress install on my web server, with no other plugins, and this same issue persisted.