Enterprise distribution ios app - cannot connect to server

I am trying to distribute my application from web server.

I have created .ipa file using enterprise distribution provisioning profile and certificate.

I have put .ipa file and manifest.plist file on server.

Server configuration :

We have configure IIS Manager with below mime types:

.ipa application/octet-stream

.plist text/xml

we have tried

.plist application/xml also.

My server is configured with ssl(and it is not self signed)

There is no authentication for these files.

My manifest.plist looks like below,

<?xml version="1.0" encoding="UTF-8"?> 
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> 
<plist version="1.0"> 
<dict>
<key>items</key> 
<array> 
<dict> 
<key>assets</key> 
<array> 
<dict> 
<key>kind</key> 
<string>software-package</string> 
<key>url</key> 
<string>https://www.example.com/appname.ipa</string> 
</dict> 
</array> 
<key>metadata</key> 
<dict> 
<key>bundle-identifier</key> 
<string>com.appname</string> 
<key>bundle-version</key> 
<string>1.0</string> 
<key>kind</key> 
<string>software</string> 
<key>title</key> 
<string>App Name</string> 
</dict> 
</dict> 
</array>
</dict> 
</plist>

now when I am clicking on below url

itms-services://?action=download-manifest&url=https://www.example.com/manifest.plist

I am getting error like below,

Cannot connect to www.example.com

Can anybody help to resolve this? Any help would be appreciated.

Actually, there was an issue with plist file. I was creating .plist file by pasting above plist code (mentioned in the question) in Text app in the mac and then was saving with .plist extension. And that might be converted to some unreadable format that my server was unable to read. For the solution, While archiving my build I have checked the checkbox Include manifest for over-the-air installation (as shown in below screenshot). and then I have provided app URL (URL for .ipa file), display image URL and full-size image URL. So, that with ipa my manifest.plist file was also generated and I have put that file without opening it and that's it!

Screenshot: