title: Can't connect to mongodb via metabase
body: <p>I'm attempting to connect to a MongoDB using Metabase.</p>
  
  <p>It's connecting through a SSH tunnel - these connection details are fine.</p>
  
  <p>The error I'm getting from metabase is:</p>
  
  <pre><code>com.mongodb.MongoTimeoutException: Timed out after 3000 ms while waiting for a server 
  that matches ReadPreferenceServerSelector{readPreference=primary}. 
  Client view of cluster state is {type=UNKNOWN, servers=[{address=&lt;redacted&gt;:40206, type=UNKNOWN, state=CONNECTING}]
  </code></pre>
  
  <p>Can anyone decipher this message?</p>