Reproducible also from Chrome 66 on Win , but appears less frequently.

This is probably caused by WebSocket throttling, which slows down new connections when there have been many failed or incomplete connections recently. If this is the issue, then ensuring that all connections are cleanly closed will resolve it.

Thanks for the quick reply, we will look into it to confirm that all connections are closed properly to see if it resolves it.

mbuerger.rlp@ Thanks for the issue.

Request you to provide another link where this issue can be reproduced, as the above given link is a bad site. We won't be able to triage this issue further with that site.

Thanks..

If a WebSocket connection is still opening, it's good to give it a chance to finish connecting so that it will be closed cleanly and not count as a connection failure. Here's an example of what I mean:

function disposeWebSocket(ws) {
  ws.onclose = ws.onerror = ws.onmessage = null;
  switch (ws.readyState) {
    case WebSocket.CONNECTING:
      ws.onopen = () => {
        ws.close();
      };
      setTimeout(() => {
        if (ws.readyState === WebSocket.CONNECTING) {
          ws.close();
        }
      }, 1000);
      return;

    case WebSocket.OPEN:
      ws.close();
      return;

    default:
      return;
  }
}

I used a timeout so that it doesn't wait too long for a connection to complete.

Closing as it looks like the problem is resolved.