title: Named Pipes Provider error on classic ASP site in VM environment
body: <p>I've recently moved a classic ASP site from a single-server IIS6 (Window Server 2003) and SQL Server 2005 setup, to a Hyper-V setup running Windows Server 2012 on the host and two VMs (single machine).</p>
  
  <p>Here is a diagram of the current setup:</p>
  
  <p><img src="https://i.stack.imgur.com/fAidJ.png" alt="enter image description here"></p>
  
  <p>My problem is that I am getting the following error intermittently:</p>
  
  <blockquote>
    <p>Named Pipes Provider: Could not open a connection to SQL Server [53].</p>
  </blockquote>
  
  <p>I've <a href="https://serverfault.com/questions/541429/do-two-vms-on-a-single-hyper-v-host-use-the-nic-when-communicating">been told</a> and was able to prove that the web-to-DB traffic never uses the physical NIC, so that should rule out any issues w/ the NIC or its drivers/configuration.</p>
  
  <p>I've also made sure that there are no IP conflicts (the host and VM IPs are all different).</p>
  
  <p>The only pattern I can detect is that it seems more likely to happen during peak periods. The odd thing is it can go 7 days without an error, and then on a single day, the error will happen on 50-100 requests, often within the same 30 seconds, or in groups of 30-second intervals.</p>
  
  <p>I've been trying to figure this out for weeks -- since migrating to the new server over 3 weeks ago. If no one here can help, my last resort is to open a ticket with Microsoft. However, I'm not optimistic they will be able to help as I'm not able to reproduce it.</p>
  
  <p>As a last resort, I'm considering moving them back to a single instance, which I'm trying my best to avoid.</p>
  
  <p><strong>Update:</strong></p>
  
  <p>Here is the connection string I'm using:</p>
  
  <pre><code>Provider=SQLNCLI11;Server=[my DB VM IP address];Integrated Security=SSPI;"
  </code></pre>