title: React-router issues with including express
body: <p>I have set up react for frontend, and for my backend i'm using express.
  I came cross with this github <a href="https://github.com/crsandeep/simple-react-full-stack" rel="nofollow noreferrer">repo</a> which is implements to be "simple react-express fullstack" So I went ahead and forked the repo, filled up with my own stuff. </p>
  
  <p>I have sign-in/sign-up form at frontend, which accordingly redirects to /auth/sign-up or /auth/sign-in with using the react router like this.</p>
  
  <pre><code>     &lt;Switch&gt;
                &lt;Route exact path="/" component={Signin}/&gt;
                &lt;Route path="/auth/sign-in" component={Signin}/&gt;
                &lt;Route path="/auth/sign-up" component={Signup}/&gt;
      &lt;/Switch&gt;
  </code></pre>
  
  <p>When I try to visit these paths when running standalone the frontend, it works. But if I run it with express, the path(s) say error 404, any ideas? Should it be acting like that? My github repo could be found <a href="https://github.com/mikk-io/2" rel="nofollow noreferrer">here</a></p>