Записки

В файл wp-config.php прописать сверху после <?php:

define('.COOKIE_DOMAIN.', 'www.mydomain.com');
define('.SITECOOKIEPATH.', '.');

if(isset($_SERVER['HTTP_X_FORWARDED_FOR'])) {
        $list = explode(',',$_SERVER['HTTP_X_FORWARDED_FOR']);
        $_SERVER['REMOTE_ADDR'] = $list[0];
  }
define( 'WP_HOME', 'https://www.mydomain.com' );
define( 'WP_SITEURL', 'https://www.mydomain.com' );
$_SERVER['HTTP_HOST'] = 'www.mydomain.com';
$_SERVER['REMOTE_ADDR'] = 'https://www.mydomain.com';
$_SERVER[ 'SERVER_ADDR' ] = 'www.mydomain.com';

if ($_SERVER['HTTP_X_FORWARDED_PROTO'] == 'https')
       $_SERVER['HTTPS']='on';