Browser is not prompting to open/save xls or xlsx when requested through httpd based proxy

Issue

• When clients request ".xls" or ".xlsx" content from our backend through our httpd based proxy, their browser is not providing the expected options to save the file or open it in a proper ".xls"/".xlsx" reading program. Instead, the browser displays unreadable byte data from the file. We get the expected open/save prompt from the browser when requesting the ".xls" content directly from the backend.