Socket hung up

###env:
1: ingress
rules:
- host: sprd.nats.service
http:
paths:
- path: /nats/scc-demo
backend:
serviceName: socketcluster
servicePort: 8000
2: socketCluster.connect({host: 'sprd.nats.service:30001/nats/scc-demo', })

###bug:
Most of the time can be connected successfully
but some times: (from chrome devtool)

WebSocket connection to 'ws://sprd.nats.service:30001/nats/scc-demo/socketcluster/' failed: WebSocket is closed before the connection is established.

Uncaught SocketProtocolError {name: "SocketProtocolError", message: "Client connection establishment timed out", code: 4007, stack: "SocketProtocolError: Client connection establishme…_communication_01/public/socketcluster.js:1457:18"}

WebSocket connection to 'ws://sprd.nats.service:30001/nats/scc-demo/socketcluster/' failed: Error in connection establishment: net::ERR_NAME_NOT_RESOLVED

Uncaught SocketProtocolError {name: "SocketProtocolError", message: "Socket hung up", code: 1006, stack: "SocketProtocolError: Socket hung up↵ at SCClien…communication_01/public/socketcluster.js:1452:20)"}

Start with the ingress rule and the socketCluster.connect URL shown in the issue, then reproduce the intermittent failure while watching Chrome DevTools. Compare successful connections with the reported WebSocket, timeout, and name-resolution errors. Done means identifying the cause of the hung-up connection and verifying reliable establishment through the shown ingress path.