socket.io server fails in scale test with artillery

Question

I am executing the scale on socket.io using artillery using the steps mentioned in the blog - https://www.artillery.io/blog/load-testing-socketio-with-artillery with following modification (adding more users)

config:
  target: "http://localhost:3000"
  phases:
      - duration: 60
        arrivalRate: 5
      - duration: 60
        arrivalRate: 5
        rampTo: 50 

I am executing the test against the code available at https://github.com/socketio/socket.io/tree/main/examples/chat

Here is the findings

engine.socketio.emit: .......................................................... 1877
engine.socketio.emit_rate: ..................................................... 2/sec
errors.ECONNREFUSED: ........................................................... 111
errors.Error: xhr poll error: .................................................. 591
errors.Error: xhr post error: .................................................. 388
vusers.completed: .............................................................. 860
vusers.created: ................................................................ 1950
vusers.created_by_name.A chatty user: .......................................... 188
vusers.created_by_name.A mostly quiet user: .................................... 282
vusers.created_by_name.A user that just lurks: ................................. 1480
vusers.failed: ................................................................. 1090
vusers.session_length:
  min: ......................................................................... 60007.8
  max: ......................................................................... 174740.5
  median: ...................................................................... 64236
  p95: ......................................................................... 161191.7
  p99: ......................................................................... 171159.6

Any idea, why it is failing for so many users?