title: Web App to SQL Server Not Connecting ( Error Locating Server/Instance Specified)
body: <p>I know this is an often asked question, but I'm still receiving this error and I have tried:</p>
  
  <ul>
  <li>Using localhost, the IP address and the instance name in the
  connection string </li>
  <li>Changing the SQL Server Configuration Manager so
  Named Pipes and TCP are both enabled Ensured the database is set to
  allow remote connections</li>
  <li>Opened 1433 &amp; 1434 for UDP &amp; TCP in Windows    Firewall, in fact I
  tried turning off the firewall for a moment to    see if it would
  connect</li>
  <li>Ensured the browser &amp; the MSSQLSERVER service    are both up and
  running using NETWORK SERVICE</li>
  </ul>
  
  <p>Now for some oddness. The SQL Server instance and the IIS running the website are on the same machine.</p>
  
  <p>If I open a browser and browse to the website I get the error. If I open a browser on my local machine and browse to the website I get the error. If I change the connection string in my development PC to the IP address of the remote server running SQL server and debug the application it connects and runs without error!</p>
  
  <p>I am totally at a loss now as to what could be the error.</p>
  
  <p>This is SQL Server 2008 RC2. </p>
  
  <p><strong>I'm on the verge of giving up - I very much appreciate the efforts you guys have made, I have tried all the suggestions here and I am coming to the conclusion that something must have gone awry in the set-up of the server, the website or the database. Just to reiterate if you remote desktop onto the server and connect to the website using <code>http://gdservers</code> you can login and it all works fine, if you use <code>http://gdservers.&lt;domain&gt;.co.uk</code> the login fails. The error in the event log is a membership credentials failure, not blocked by firewall or anything like that. If there's any other suggestions I'd love to hear them, thanks again.</strong></p>