Hi,
What is your website type, File-Based or IIS-Based? If it is File-Based, it doesn't need IIS support.
What antivirus software are you using? Some Antivirus Softwares or Firewalls contain Web Access Protection which disables the dynamic port of ASP.NET Development Server or IIS.
If this doesn’t help you, please feel free to let me know.
I hope this helps.
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