We have a website developed on ASP.NET that uses Silverlight to stream videos. All is working well when accessed externally, however, when accessed from the local network, it will not play the media (video or audio). We have attempted to switch to a different web server on the same network and it still not work. To add to the confusion, we have some desktops that will play the media from Chrome, occasionally, but we could never get it to work from IE or Firefox. The problem is also being seen on our other sites developed in ASP.NET.

Here is a sample of the code being used to call one particular video:

    <%@ Page Language="vb" AutoEventWireup="false" CodeBehind="SixPoint.aspx.vb" Inherits="HomeTeam.Web.SixPoint" %>
    If Not Request.IsAuthenticated Then
    End If

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <!--#include file="Header_incl.aspx" -->
    <style type="text/css">
    html, body {
        height: 100%;
        overflow: auto;
    body {
        padding: 0;
        margin: 0;
    #silverlightControlHost {
        height: 100%;
    <script type="text/javascript" src="Silverlight.js"></script>
    <script type="text/javascript">
        function onSilverlightError(sender, args) {
            var appSource = "";
            if (sender != null && sender != 0) {
                appSource = sender.getHost().Source;
  • My first guess would be a split-scope DNS issue. Can you resolve the external name of the webserver from inside your network? – HopelessN00b Apr 1 '14 at 15:08
  • When we resolve the name of the webserver from inside the network, it gives the private IP address. Our internal DNS has reverse and forward zones are pointing to the private IP. When I change the DNS server on my machine to an external DNS server will resolve the external IP, but the page will not pull up at all. – mikerdz Apr 1 '14 at 16:01
  • IS it possible that the video/Silverlight file is referencing the external IP of the webserver somewhere/somehow? Would explain why you get the same symptoms for the video file as you do for the website, accessing the external address from internal. – HopelessN00b Apr 1 '14 at 16:04
  • Unfortunately, I did not build the site and the developer refuses to take responsibility for it. We have discussed the issue with her and explained to her that the site is accessible from both ends, and the media should be accessible as well. Level 3 network guy and myself (sys admin) believe it is something in the way the site calls the video, but she insists her code is properly developed. I am just trying to find an alternative to my argument for her benefit. – mikerdz Apr 1 '14 at 16:31
  • On another note, we have migrated the settings to a secondary IIS server and the same symptoms follow the site. The 4 sites she developed with the same code/structure are having the same problem with the media files. It is believed that before I started here in January the files worked, however, shortly before my onboarding it stopped working. Nobody can give me a definite yes or no to this "rumor." – mikerdz Apr 1 '14 at 16:34

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