Thank you, everyone.
Before asking for help here on the forum, I used Claude to go through Netino's procedure and tested it on a fresh VPS with CWP installed. The procedure worked, but I discovered two issues:
Roundcube webmail redirect issue: Accessing host.domain.com or mail.domain.com works correctly. However, when I access domain.com/webmail, the Roundcube login interface opens normally, but after entering my email address and password, I am automatically redirected to domain.com instead of being logged into Roundcube.
High process usage in CWP: After following the procedure, I noticed that the number of running processes in CWP started increasing significantly. In my case, the server was running PHP 8.3, although I am not sure whether the PHP version is related to this issue.
Has anyone experienced similar issues or knows what might be causing them?
Thank you for your help.