The request was aborted: the request was canceled. Vb.net

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VB

Dim request As System.Net.HttpWebRequest = System.Net.HttpWebRequest.Create("https://api.test.payadvantage.com.au/v3/token")
request.Method = "POST"
request.ContentType = "application/x-www-form-urlencoded"
request.ContentLength = 94
request.KeepAlive = True
request.ContinueTimeout = 10000
request.Host = "api.test.payadvantage.com.au"
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12
Dim outgoingQueryString As NameValueCollection = HttpUtility.ParseQueryString(String.Empty)
outgoingQueryString.Add("grant_type", "password")
outgoingQueryString.Add("username", username)
outgoingQueryString.Add("password", password)
 Dim postBytes As Byte() = New UTF8Encoding().GetBytes(outgoingQueryString.ToString())


Try
    Using requestStream = request.GetRequestStream()
      requestStream.Write(postBytes, 0, postBytes.Length)
End Using
Catch ex As Exception

    Dim MessageInput as string = ex.Message
    Dim MessageOutput as String = Regex.Replace(MessageInput, "'", " ")
    tblBillingAccount.GetControl(Of MTTextBox)("ISOScope").Value = "Auth Fail " + MessageOutput
End try

Try
     Using response = CType(request.GetResponse(), HttpWebResponse)
     accessToken = response.StatusDescription
End Using
Catch ex As Exception
    Dim MessageInput as string = ex.Message
    Dim MessageOutput as String = Regex.Replace(MessageInput, "'", " ")
    tblBillingAccount.GetControl(Of MTTextBox)("ISONotApplicable").Value = "Auth Fail " + MessageOutput

End try

What I have tried:

Some of the parameters are included from Pay Advantage Documentation. ie keep alive and content length. I have tried multiple security protocols and this is the only one that does not return an error.

Urgently need some help to get this project over the line. Thanks in advance.