PDF file download issue in IOS devices after registered web application in Azure Application Proxy.

I have a web application developed in .Net and Sql server and successfully deployed in UAT server and its working fine.

Converting this Intranet web application to internet web application , we registered this intranet web application in Azure Application Proxy.

Then we have an issue in the download PDF files in IOS (iPhone or iPAD) devices in Edge browser.

Need some one's help to fix these issue.