Express, HTTPS WebSockets, and IISNode

Question

I have a very basic Express server that also has an HTTPS WebSocket server running on the same port. When I run this locally I'm able to hit the express endpoints and establish a connection between the WebSocket server and the client over https.

However, when I host this on IIS (Site is pointing to the correct path and bindings are established. WebSocket module is correctly configured. Works locally and deployed using http websockets). I can't establish the connection. I've read a few threads on this primarily HTTPS and iisnode and feel like my lack of understanding of how IIS handles https is the culprit here... I see that I'm establishing the server the same way as the original poster, but I'm struggling to see how I can establish the WebSocketServer without it.

index.js (relevant code only)

// Create express app.
var app = express();

// Open the logfile in append mode.
var logFile = fs.createWriteStream(LOG_PATH, { flags: 'a' });

const keyPath = fs.readFileSync(KEY_PATH, 'utf8');
const certPath = fs.readFileSync(CERT_PATH, 'utf8');
const credentials = { key: keyPath, cert: certPath };

// Create HTTPS server
const server = https.createServer(credentials, app);

// Attach WebSocket server to the HTTPS server
const wss = new WebSocketServer({ server, perMessageDeflate: false });

// Run the express app on the IIS Port.
server.listen(PORT, () => {
    logger('INFO', `Express Server Started, PORT: ${PORT}`);
});

wss.on('connection', (ws) => {
    logger('INFO', `Client has connected via Web Socket.`);

    ws.send('Hello from the server!');

    ws.on('message', function message(data) {
        logger('INFO', data.toString());
    });

    ws.on('close', () => {
        logger('INFO', `Client has disconnected.`);
    });
});

web.config

<configuration>
  <system.webServer>
    <handlers>
      <add name="ExpressServer" path="index.js" verb="*" modules="iisnode" resourceType="Unspecified" />
    </handlers>
    <webSocket enabled="true" />
    <rewrite>
      <rules>
        <rule name="sendToNode">
          <match url="/*" />
          <action type="Rewrite" url="index.js" />
        </rule>
      </rules>
    </rewrite>
  </system.webServer>
</configuration>