Sending message to Telegram Error: The underlying connection was closed: An unexpected error occurred on a receive

This is the url that i have referred in order to send a message to telegram. https://medium.com/javarevisited/sending-a-message-to-a-telegram-channel-the-easy-way-eb0a0b32968

Meanwhile, i have got the api key from BotFather.

This is the returned error when I executed my code.  The underlying connection was closed: An unexpected error occurred on a receive.

Private Function send() As Boolean 
    Try 
        Dim urlString As String = "https://api.telegram.org/bot{0}/sendMessage?chat_id={1}&text={2}"
 
        Dim apiToken As String = "6076412963:AAGy2bP3SGzeOBK_c6nH6nT5ubS6rjAPzi8"
        Dim chatId As String = "109780439"
        Dim text As String = "Hello world!"
        urlString = String.Format(urlString, apiToken, chatId, text)
        Dim request As WebRequest = WebRequest.Create(urlString)
        Dim rs As Stream = request.GetResponse().GetResponseStream()
        Dim reader As StreamReader = New StreamReader(rs)
        Dim line As String = ""
        Dim sb As StringBuilder = New StringBuilder()
 
        While line IsNot Nothing
            line = reader.ReadLine()
            If line IsNot Nothing Then sb.Append(line)
        End While
 
        Dim responseString As String = sb.ToString()
 
        Response.Write(sb.ToString())
 
    Catch ex As Exception
        Response.Write(ex.Message)
    End Try 
End Function