When logging in on the new link, the page just refreshes

I am trying to use this plugin to change the login page for the site, as we are getting a lot of brute force attempts.
It isn’t just this plugin that isn’t working, using the option to do the same in iThemes Security (Better WP Security) gives the same result, as does attempting to make the change manually.

So when I change the address from example.com/wp-login.php to example.com/example it blocks wp-login.php. When you load example.com/example it comes up with the login form but when you fill it in and hit submit it just reloads the page (with a correct user and pass or an incorrect user and pass) with no error message.

I have tried it with a site set up locally on a site a few weeks old (but with all the plugins set up) as well and it did work properly there, which makes me thing that it’s perhaps something server side?

Same issue on: MacOS: Opera, Google Chrome and Safari. Android 6.0.1: Opera and Chrome. And iOS 10.2.1: Safari, Blu and Opera Mini.
Security plugin wise, we have wordfence security, iThemes security and Authy TFA