Laravel WebSockets: Subscribing to private channels does not work

Software:

• Laravel 5.8
• Laravel WebSockets 1.1
• Vue 2.6.10

In websockets.php (complete file) I have my local_cert and local_pk setup with my certificates. If I leave this option blank I cannot even connect. I also have set verify_peerto false, because if I don't I cannot connect either.

broadcasting.php:

'pusher' => [
        'driver' => 'pusher',
        'key' => env('PUSHER_APP_KEY'),
        'secret' => env('PUSHER_APP_SECRET'),
        'app_id' => env('PUSHER_APP_ID'),
        'options' => [
            'cluster' => env('PUSHER_APP_CLUSTER'),
            'host' => '127.0.0.1',
            'port' => 6001,
            'scheme' => 'https',
            'curl_options' => [
                CURLOPT_SSL_VERIFYHOST => 0,
                CURLOPT_SSL_VERIFYPEER => 0,
            ]
        ],
    ],

If I get rid of the curl options I get an empty Broadcast exception like described here.

bootstrap.js:

window.Pusher = require('pusher-js');
window.Echo = new Echo({
    broadcaster: 'pusher',
    key: '7d23096ae0ab2d02d220',
    wsHost: window.location.hostname,
    wsPort: 6001,
    wssPort: 6001,
    encrypted: true,
    disableStats: true,
    auth: {
        headers: {
            'X-CSRF-TOKEN': window.App.csrfToken,
        },
    },
})

This is all I get from the logs after running php artisan websockets:serve:

New connection opened for app key 7d23096ae0ab2d02d220.
Connection id 49092664.114416323 sending message {"event":"pusher:connection_established","data":"{\"socket_id\":\"49092664.114416323\",\"activity_timeout\":30}"}

What I should get is messages about listening / joining channels and sending messages etc. But all of that does not work at the moment. I have things like:

Echo.private('notifications.' + this.user.id)
                .listen('UserNotificationSent', (e) => {
                    console.log(e)
                })

Events: UserNotificationSent.php for example.

Of course internally I have everything else setup as well: channels with auth, etc. Everything worked locally on my machine on a lower Laravel version (5.4). But I recently updated to 5.8 and deployed to a server and now I struggle with this.

I also opened an issue on github.

IMPORTANT UPDATE This is actually not due to the deployment, I have the same problem on my local setup. What is interesting is that listening to channels via Echo.channel() works, however, .private() is not working. On Github (link above) I came across a guy who has the exact same problem. We did not find a solution yet.

I found the problem.

I had this in my web.php:

Route::post('/broadcasting/auth', function (Illuminate\Http\Request $req) {
if ($req->channel_name == 'users') {
    return Broadcast::auth($req);
}
});

I don't exactly remember why and when I added this, but it was probably from here. For some reason this didn't generate any errors. Anyway, I got rid of this and now it´s working like a charm.