Laravel web socket with pusher does not work

I am trying to use websocket with pusher for live notification.
It was working perfect yesterday and suddenly it stopped working

WebSocket connection to 'ws://www.domain.com:6001/app/ap1?protocol=7&client=js&version=4.4.0&flash=false' failed: Error in connection establishment: net::ERR_CONNECTION_REFUSED

But when I run $php artisan websockets:serve I get this in terminal:

Terminal output

my bootstrap.js file look like this

import Echo from 'laravel-echo'
window.Pusher = require('pusher-js');

window.Echo = new Echo({
broadcaster: 'pusher',
key: 'ap1',
cluster: 'us2',
wsHost: window.location.hostname,
wsPort: 6001,
encrypted : false,
disableStats: true,
enabledTransports: ['ws', 'wss'],
});

.env pusher configuration is like this

PUSHER_APP_ID=12345
PUSHER_APP_KEY=ap1
PUSHER_APP_SECRET=1234567
PUSHER_APP_CLUSTER=us2

and broadcasting.php file look like this

'connections' => [

        'pusher' => [
            'driver' => 'pusher',
            'key' => env('PUSHER_APP_KEY'),
            'secret' => env('PUSHER_APP_SECRET'),
            'app_id' => env('PUSHER_APP_ID'),

              'options' => [
              'cluster' => 'us2',
              'encrypted' => false,
              'host' => 'http://example.com/',
              'port' => 6001,
              'scheme' => 'http'

                ],


        ],

        'redis' => [
            'driver' => 'redis',
            'connection' => 'default',
        ],

        'log' => [
            'driver' => 'log',
        ],



'null' => [
        'driver' => 'null',
    ],

],

];

App is running on docker container.

Please guide me where I am doing wrong, Any help guys.

Source: StackOverflow