If you’re using the Better WP Security plugin for WordPress then you’re probably wanting to change your backend link from /wp-admin/ to /secret-dashboard or something. However if you have Varnish installed this can lead to problems.With Varnish installed it will want to redirect you to something like
http://your-site.com:8080/wp-login.php?345sdf25235safsfjasdf
It’s a pretty simple fix, all you have to do is open your Nginx Configuration probably under /etc/nginx/sites-available/default and add the following to your server block:
port_in_redirect off;
Restart Nginx and Varnish and your WordPress should now redirect correctly!