Trouble changing url login page

Hello,

I’m using All in One Security on several web sites.

I’m currently working on one of those sites.
I’ve installed this plugin a few weeks ago, changed the url login page: everything was ok.
Last week, I improved the security level of the plugin, everything was still working perfectly. And suddently, couple of hours later, I’ve been logged out with no possibility to go back to the dashboard.
I could’nt reach the new url login page > sent me on the home page, and of course, wp-admin and wp-login.php weren’t working anymore.
I thought there might be a problem with my IP, so I asked a friend to try to log in from another one, but she couldn’t reach the page neither.

I removed All In One from FTP panel so I’ve been able to reach the dashboard again after all, but each time I try to reactivate All In One and create a new login url I have the same problem. I can’t reach the login page.

There’s nothing left in my .htaccess file concerning All In One.

What do you suggest ?

All in One is working just fine on my other sites: same host, same WP version, same theme (Bridge Qode).

Thank you so much for your help !