It will only work for you when you login to your server first.
However, it would not work for other users (in general).
Because other user did not know that they need to login to your server before there access the above page.
I will be re-direct to a login page when I try to access http://18.104.22.168/~lookangc/index.php?action=dlattach;topic=1009.0;attach=1107
You need to provide an URL which is open to public (without login requirement).