asp.NET 4.8 WebRequest errors with "The underlying connection was closed: An unexpected error o-CodePudding

On one particular website on my web server WebRequests have started throwing the following error: "The underlying connection was closed: An unexpected error occurred on a send."

My asp.NET website is running framework version 4.8.
I am requesting a page on the same website that is doing the request.
This code has been in place for years and has suddenly stopped working on this website
This same code works fine on a different website running on the same webserver

Request code:

Dim myReq As System.Net.WebRequest = System.Net.WebRequest.Create("https://example.com")
myReq.Method = "GET"

myReq.ContentType = "text/html; encoding='utf-32'"


Dim wr As System.Net.WebResponse = myReq.GetResponse()
Dim receiveStream As System.IO.Stream = wr.GetResponseStream()
Dim reader As System.IO.StreamReader = New System.IO.StreamReader(receiveStream, Encoding.UTF8)
Dim content As String = reader.ReadToEnd()

I have tried adding the following to the page doing the request, and the global.asax, but it did not work. It should not be required, though, because I am using .net 4.8:

System.Net.ServicePointManager.SecurityProtocol = System.Net.SecurityProtocolType.Tls12

CodePudding user response：

As mentioned in the comments, this is often an issue with the internal DNS or a HOSTS file entry. Either the server is resolving the site's domain to the wrong internal address, or it's trying to access the site's public address and confusing the router.