title: "Login failed for user" when specifying default port
body: <p>Trying to debug a customer's connection problem when they try specifying the SQL Server port.</p>
  
  <p>Reproducing the issue locally I checked and my server runs under the default 1433 port. Specifying that port using:</p>
  
  <pre><code>SqlConnectionStringBuilder builder = new SqlConnectionStringBuilder();
  builder.DataSource = "servername,1433";
  builder.InitialCatalog = databaseName;
  builder.IntegratedSecurity = false;
  builder.UserID = userName;
  builder.Password = UserPsw;
  </code></pre>
  
  <p>This fails with "Login failed for user". If I remove the port number, it connects fine. Why does this happen?</p>
  
  <p>By the way the same happens with Windows Integrated Security.</p>
  
  <p>And one more piece of information: I do run also a SQL Server 2005 express SQL server on the same box.</p>