title: Unable to connect to SQL Express "Error: 26-Error Locating Server/Instance Specified)
body: <p>I am at an loose end with one particular box that is running SQL Server 2008 R2 Express.</p>
  
  <ul>
  <li>Windows Firewall is configured to allow inbound TCP &amp; UDP 1433, 1434.</li>
  <li>Windows Firewall is configured to allow outbound TCP &amp; UDP on any port.</li>
  <li>No other software AV/FW is currently running.</li>
  </ul>
  
  <p>When I try to connect to <code>xxx.xxx.xxx.xxx\sqlexpress</code>, it times out with the following error:</p>
  
  <blockquote>
    <p>TITLE: Connect to Server</p>
    
    <p>Cannot connect to xxx.xxx.xxx.xxx\SQLEXPRESS.</p>
    
    <p>ADDITIONAL INFORMATION:</p>
    
    <p>A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified) (Microsoft SQL Server, Error: -1)</p>
  </blockquote>
  
  <p>I have checked that remote connections are allowed on the server.</p>
  
  <p>I have confirmed TCP/IP is enabled and configured in SQL Server Configuration to allow connections on the external IP to 1433.</p>
  
  <p>I have also used Wireshark from my local machine and I can see requests for 1433 UDP going to the remote server.</p>
  
  <p>But using Wireshark on the remote server shows no inbound connection requests for 1433 UDP or anything from my external IP (with filtering to remote RDP from results).</p>
  
  <p>This makes me think it is a firewall issue.</p>
  
  <p>The server is hosted by an external company who have control over the PIX in front of our server.</p>
  
  <p>I need to troubleshoot this as much as possible myself as the hosting company have no clue what they are doing.</p>