title: Pusher auth endpoint gives me a 404 error
body: <p>I am using <code>pusher-js</code> in react. My frontend is served at app.xxx.com and my backend is served at api.xxx.com. We have a private notification websocket channel to push notiifcations through app.xxx.com. What i'm trying to achieve is using the auth endpoint on backend. But no matter what i do, pusher will always request to the base URL of frontend plus auth endpoint. In my case it will be <code>https://app.xxx.com/broadcasting/auth</code> but i want it to be <code>https://api.xxx.com/broadcasting/auth</code>. What should i do? Here's my pusher config:</p>
  <pre><code>pusher = new Pusher(APP_ID, {
                  httpHost: process.env.REACT_APP_WS_HOST,
                  authEndpoint: '/broadcasting/auth',
                  auth: {
                      params: {
                          id: userData.id,
                      },
                      headers: {
                          'X-CSRF-Token': '{{ csrf_token() }}'
                      }
                  },
                  cluster: 'ap2',
                  wsHost: process.env.REACT_APP_WS_HOST,
                  wsPort: 6001,
                  wssPort: 6001,
                  forceTLS: true,
              })
  </code></pre>
  <p>The value of <code>process.env.REACT_APP_WS_HOST</code> is <code>api.xxx.com</code></p>
  <p><strong>UPDATE</strong>:<br />
  I even tried adding an <code>authHost</code> key but nothing changed.</p>