Multisite: Redirect to appropriate domain if subdomain doesn’t exist
If you want all unregistered subdomains to redirect to the main domain site: function prevent_multisite_signup() { $domain = $_SERVER[‘HTTP_HOST’]; $domain = explode(‘.’, $domain); $domain = array_reverse($domain); $domain = “$domain[1].$domain[0]”; wp_redirect($domain, 301); exit; } add_action(‘signup_header’, ‘prevent_multisite_signup’);