Administrative isolation means moving the WordPress admin off its default `/wp-admin` location and restricting who can reach it at all — typically by IP allow-list, VPN-only access, or routing the admin to a private subdomain that the public site doesn't even know about.
The reason to bother is simple: the default WordPress login URL is the most-attacked surface on a WordPress site. Bot networks hammer it constantly looking for weak credentials, plugin vulnerabilities, and old PHP versions. Removing that front door doesn't make a site invulnerable, but it eliminates an entire category of attack traffic before it ever reaches your stack.
I use it on client builds where the editorial team is small, internal, and predictable — media organisations, government departments, larger education sites where logins come from a known network. It's a poor fit when you have hundreds of contributors signing in from coffee shops; in that case you want strong MFA and rate limiting at `/wp-login.php` instead of full isolation.
The real version of the work involves a few moving parts: the rewrite or routing rule that hides `/wp-admin`, the access control layer (IP, VPN, or basic auth at the edge), monitoring so you notice when a legitimate admin gets locked out, and a documented break-glass path for emergencies. None of that is exotic, but it's all easy to get half-right.