VB.Net Web Scraper - 请求被中止 : Could not create SSL/TLS secure channel

Question

我正在开发一个网络抓取程序，在禁用 Tls 1.0 和 1.1 并启用 Tls 1.2 和 1.3 的网站上出现以下错误:
'请求被中止:无法创建 SSL/TLS 安全通道'
我还应该注意，我使用的是 .Net 4.8 版
这是我用来检查的网站:
https://www.cdn77.com/tls-test
我已经阅读了近十几篇关于该主题的帖子，但没有一个解决方案对我有用。
这是代码。它适用于大多数网站:

        Try
            ServicePointManager.Expect100Continue = True
            ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 Or 
                                                    SecurityProtocolType.Tls13

            Dim address = New Uri(url)

            Using client = New WebClient()
                Dim stream = client.OpenRead(address) ' This is where exception is caught
                Using sr = New StreamReader(stream)
                    Dim page = sr.ReadToEnd()
                    Return page
                End Using
            End Using

        Catch ex As Exception
            Return ex.Message
        End Try

Answer 1

我想你不会找到那么多只有 TLS1.3 的网站
我使用这个功能很多年了:

  Function getFromURL(ByVal url As String) As String
        Dim request As System.Net.WebRequest = System.Net.WebRequest.Create(url)
        'request.Headers.Add("HTTP_USER_AGENT", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 2.0.40607; .NET CLR 1.1.4322; .NET CLR 2.0.50215)")
        System.Net.ServicePointManager.SecurityProtocol = System.Net.SecurityProtocolType.Tls12
        Dim response As System.Net.WebResponse

        response = request.GetResponse()

        Dim responseStream As System.IO.Stream = response.GetResponseStream()

        Dim reader As System.IO.StreamReader = New System.IO.StreamReader(responseStream)

        Return reader.ReadToEnd()

    End Function