title: Nest.js WebSocket returns Transport unknown
body: <p>I have backend on NestJS and frontend on Angular 8. When I try connect websocket, backend returns:
  <code>{&quot;code&quot;:0,&quot;message&quot;:&quot;Transport unknown&quot;}</code></p>
  <p>I have NestJS 7.4.3:</p>
  <pre><code>&quot;@nestjs/common&quot;: &quot;~7.4.3&quot;,
  &quot;@nestjs/core&quot;: &quot;~7.4.3&quot;,
  &quot;@nestjs/platform-express&quot;: &quot;~7.4.3&quot;,
  &quot;@nestjs/platform-socket.io&quot;: &quot;^7.4.3&quot;,
  &quot;@nestjs/websockets&quot;: &quot;^7.4.3&quot;,
  &quot;@types/socket.io&quot;: &quot;^2.1.11&quot;,
  </code></pre>
  <p>Gateqay:</p>
  <pre><code>@WebSocketGateway({ path: '/ws', transports: ['polling', 'websocket'] })
  </code></pre>
  <p>why is it not working?</p>