title: gcp: insecure grpc connection does not work inside gcp
body: <p>A grpc connection between two microservices is to be established within gcp.
  Both services are provided in a Docker container.
  When tested locally within a Docker Network, the connection (and the function call) works.</p>
  <p>No connection is established within Google Cloud Platform.
  However, both services are still in the same cloud network.
  We also use the standard port 443, which is specified by Google.
  There is currently no authentication.</p>
  <pre><code>func ConnectGrpc() (err error) {
  grpcClient, err := grpc.Dial(&quot;xyz:443&quot;, grpc.WithTransportCredentials(insecure.NewCredentials()))
  
  if err == nil {
      GrpcClient = grpcClient
  }
  
  return err
  }
  </code></pre>
  <p>The code shown will not create a grpc connection inside grpc. Both services (server and this client) start up.
  As soon as the client tries to call a function on the server, the service crashes.
  As I said, it can run in a local Docker network.</p>
  <p>If anyone was able to connect, how did you do it?</p>