Hi @Ching Song Lim ,
Did this problem appear for all kinds of file format or specific file format?
Try to check if the firewall is blocking the request.
You can try to edit the Hosts file of computer and add domain name's entry resolving IIS web server IP address. The Hosts file location is: C:\Windows\system32\drivers\etc\hosts
Just checking in to see if the information was helpful. Please let us know if you would like further assistance.
If the response is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.