I have done a fresh installation of Debian 11.1 and myvestacp on my OVH vps ( before I was on debian 8 with php 5.6 and Vestacp

1/ since then I have some issues with wordpress plugins, I had deactivated them for the moment...
WP Hide & Security Enhancer: rewrite function (theme, plugins...) break my website
Wordfence Security: Optimize Wordfence Firewall > Apache + CGI/FastCGI (recommended based on our tests) > The changes have not yet taken effect. If you are using LiteSpeed or IIS as your web server or CGI/FastCGI interface, you may need to wait a few minutes for the changes to take effect since the configuration files are sometimes cached. You also may need to select a different server configuration in order to complete this step, but wait for a few minutes before trying. You can try refreshing this page.
I may have forgotten to configure something during the fresh installation? Maybe both issues are related?
2/ Also I cannot log in to my email address on my email client ( but on roundcube webmail I can send and receive mails ). The problematic domain name is installed on an additional IP.
Should I use the recommended server or domain hostname settings ? Admin can you do a tutorial about email configuration

Thank you
