[SuperZen]

package.json

{
  "name": "ws-seq-para",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "dependencies": {
    "ws": "^7.2.3"
  }
}

server.js

const WebSocket = require('ws')
const wss = new WebSocket.Server({ port: 2999 })
wss.on('connection', function connection(ws) {
  ws.send(JSON.stringify({ type: 'long' }))
  setTimeout(() => {
    ws.send(JSON.stringify({ type: 'short' }))
  }, 1000)
})

client.js

const WebSocket = require('ws')
const ws = new WebSocket('ws://localhost:2999')
ws.on('message', function incoming(json) {
  const { type } = JSON.parse(json)
  switch (type) {
    case 'long':
      console.log('long start')
      setTimeout(console.log, 2000, 'long stop')
      break
    case 'short':
      console.log('short running')
      break
    default:
      break
  }
})

вывод консоли:
long start
short running
long stop

резюме: нужен queue... воркер не решает эту проблему...