We are able to successfully redirect a user to a webpage once the user exhausts the quota. But we are unable redirect HTTPS requests (the HTTPS requests are blocked, but we want those requests to be redirected to a webpage as well).
Is there any way to achieve this?
I am afraid redirecting HTTPS is not supported. Even if it was possible, the browser most likely would not allow the user to follow such redirect.
For example, if a user tries to open https://www.google.com, the software could intercept that connection and respond with a self-signed certificate, at which point the browser would warn the user about possible security risk. There is usually a button to continue, but it's rather hidden in the latest Chrome and Firefox. In addition, most users would be afraid to proceed out of fear of compromising their security, and rightly so.