exchange/app/Providers/BroadcastServiceProvider.php

<?php

namespace App\Providers;

use Illuminate\Support\ServiceProvider;
use Illuminate\Support\Facades\Broadcast;

class BroadcastServiceProvider extends ServiceProvider
{
    /**
     * Bootstrap any application services.
     *
     * @return void
     */
    public function boot()
    {
        //Broadcast::routes();
        Broadcast::routes(["middleware" => ["auth:api"]]);

        require base_path('routes/channels.php');
    }
}