title: Apollo client query error: "Network error: Failed to fetch" How to troubleshoot?
body: <p>An Apollo server is setup, and it responds correctly to the query when using graphiql.</p>
  
  <p>An existing react-redux app with server side rendering needs to start using graphql and make this query.</p>
  
  <p>A component of this app has been setup to do the same query, it seems to be doing the network request, but it fails with
  <code>
  Error: {"graphQLErrors":[],"networkError":{},"message":"Network error: Failed to fetch"}
  </code></p>
  
  <p>Any troubleshooting advice?</p>