it seems that the header in echo is missing

Echo.connector.pusher.config.auth.headers['Authorization'] = 'Bearer token';

You can check below link for further details. https://github.com/tlaverdure/laravel-echo-server/issues/129#issuecomment-284216291

@skynet-technologies i dont use pusher and problem is no request is sent to the '/api/auth/custom', with header or not

The above code was an example which means, we have to pass a header with authentication(using bearer) You can check the below code and implement your code within it.

window.Echo = new Echo({
            broadcaster: 'socket.io',
            host: HOST_FOR_YOUR_SERVER,
            auth: {
                headers: {
                    Authorization: 'Bearer ' + AUTH_API_TOKEN,
                },
            },
        });

BroadcastServiceProvider:

Broadcast::routes(['middleware' => ['auth:api']]);

For more reference, you can check the below URL https://github.com/laravel/framework/issues/23268#issuecomment-443986055