title: Intermittent connection timeouts to Solr server using SolrNet
body: <p>I have a production webserver hosting a search, and another machine which hosts the Solr search server (on a subnet which is in the same room, so no network problems). All is fine >90% of the time, but I consistently get a small number of <code>The operation has timed out</code> errors.</p>
  
  <p>I've increased the timeout in the SolrNet init to <strong>30</strong> seconds (!)</p>
  
  <pre><code>SolrNet.Startup.Init&lt;SolrDataObject&gt;(
      new SolrNet.Impl.SolrConnection(
          System.Configuration.ConfigurationManager.AppSettings["URL"]
      ) {Timeout = 30000}
  );
  </code></pre>
  
  <p>...but all that happened is I started getting this message instead of <code>Unable to connect to the remote server</code> which I was seeing before. It seems to have made no difference to the amount of timeout errors.</p>
  
  <p>I can see <em>nothing</em> in <em>any</em> log (believe me I've looked!) and clearly my configuration is correct because it works most of the time. Anyone any ideas how I can find more information on this problem?</p>
  
  <p><strong>EDIT:</strong></p>
  
  <p>I have now increased the number of HttpRequest connections from 2 to 'a large number' (I see up to 10 connections) - but this has had no discernible effect on this problem.</p>
  
  <p>The firewall is set to allow ANY connections between the two machines.</p>
  
  <p>We've also checked the hardware with our server host and there are no problems on the connections, according to them.</p>
  
  <p><strong>EDIT 2:</strong></p>
  
  <p>We're still seeing this issue.</p>
  
  <p>We're now logging the timeouts and they're mostly just over 30s - which is the SolrNet layer's timeout; some are 20s, though - which is the Tomcat default timeout period - which suggests it's something in the actual connection between the machines.</p>
  
  <p>Not sure where to go from here, though - they're on a VLAN and we're specifically using the VLAN address - response time from pings is ALWAYS &lt;1ms.</p>