Reverse Proxy works for HTML but not working for application

Hi, I have two domains lets say https://www.abc.com (external) and https://www.xyz.com (internal) . I am trying to setup a reverse proxy so the user coming to https://www.abc.com/dept1 are redirected to https://dept1.xyz.com but user always sees response coming back from https://www.abc.com/dept1.

I tried creating a rewrite profile with URL translation and local traffic policy. This works great for html pages but does not work for our application. User makes an https request to https://www.abc.com/dept1 that's terminated at F5. F5 then makes request to https://dept1.xyz.com, the server hosting the application. Can anyone one guide me how to implement this or at least how to troubleshoot why it's failing? Currently user just get connection failed message.

Thanks in advance.