如何使用具有多个用户定义结构数据库的md5哈希自定义Laravel 5.8身份验证？

Question

My case is like this, making a new application from an old application that already exists. The new application as an independent application uses its own database, but for authenticating credentials it uses the old application database. So I use a custom auth, but I'm having problems. My problem when checking the Auth::check() value is true but when redirected to the home page, the Expired Page appears. After I check Auth::check() again, the result is false. I feel there is something wrong with implementing UserProvider, but I haven't managed to implement it yet. I have modified the environment for multiple databases, and have successfully connected.

I have modified the environment for multiple databases, and have successfully connected. I've changed the config\database.php file. I modified and added the database connection used. Then I modified the config\auth.php. Credentials for logging in using "username" and "password". The "hints" field is a form of the default plain password when resetting a password. Encrypt the password using the md5 hash with the following composition:
$password = md5(md5(<input-password>.salt).salt)

The App namespace is FKQuiz.

I've modified some files : config\auth.php

'defaults' => [
        'guard' => 'siakad',
        'passwords' => 'sc_user',
    ],

'guards' => [
        'siakad' => [
            'driver' => 'session',
            'provider' => 'usersiakad',
        ],

        'api-siakad' => [
            'driver' => 'token',
            'provider' => 'usersiakad',
            'hash' => false,
        ],
    ],

'providers' => [
        'usersiakad' => [
            'driver' => 'eloquent',
            'model' => FKQuiz\Models\UserSiakad::class,
        ],
    ],
'passwords' => [
        'sc_user' => [
            'provider' => 'usersiakad',
            'expire' => 30,
        ],
    ],

Table structure :

+--------+----------+----------+--------------+----------------+---------------+
| userid | username | password |    hints     |     salt       |  tokenreset   |
+--------+----------+----------+--------------+----------------+---------------+

Modified app\Models\UserSiakad.php

<?php

namespace FKQuiz\Models;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Notifications\Notifiable;
use Illuminate\Contracts\Auth\Authenticatable as AuthenticableContract;
use Illuminate\Auth\Authenticatable as AuthenticableTrait;
use Illuminate\Foundation\Auth\User as Authenticatable;

class UserSiakad extends Authenticatable implements AuthenticableContract
{
    use Notifiable, AuthenticableTrait;

    protected $connection = 'pgsiakad';

    protected $table = 'gate.sc_user';

    protected $hidden = [
        'password', 'salt',
    ];

    public function getAuthPassword()
    {
        return bcrypt($this->password);
    }

    protected function credentials(Request $request)
    {
        return [
            $this->username() => $request->get('username'),
            'password' => md5($request->get('password'))
        ];
    }

    public function validateCredentials(UserContract $user, array $credentials)
    {
        $plain = $credentials['password'];
        return $this->hasher->check($plain, $user->getAuthPassword());
    }
}

File app\Http\Controllers\AuthSiakad\LoginController.php

<?php

namespace FKQuiz\Http\Controllers\AuthSiakad;

use FKQuiz\Http\Controllers\Controller;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\Auth;
use FKQuiz\Models\UserSiakad;

class LoginController extends Controller
{
    public function __construct()
    {
        $this->middleware('guest')->except('logout');
    }

    public function username()
    {
        return 'username';
    }

    public function showLoginForm()
    {
        return view('authSiakad.login');
    }

    public function login(Request $request)
    {
        $u = UserSiakad::where('username', '=', $request->username)->first();
        $s = $u->salt;
        $credentials = [
            $this->username() => $request->get('username'),
            'password' => md5(md5($request->get('password').$s).$s)
        ];

        if (Auth::attempt($credentials)){
            // If login succesful, then redirect to their intended location
            return redirect()->intended(route('home'));
        }
        // If Unsuccessful, then redirect back to the login with the form data
        return redirect()->back()->withInput($request->only('username', 'remember'));
    }

    protected function credentials(Request $request)
    {
        return [
            $this->username() => $request->get('username'),
            'password' => md5($request->get('password'))
        ];
    }

    public function validateCredentials(UserContract $user, array $credentials)
    {
        $plain = $credentials['password'];
        return $this->hasher->check($plain, $user->getAuthPassword());
    }
}

File routes\web.php

Route::get('/', function () {
    return view('welcome');
});

Route::get('/', 'HomeController@index')->name('home');
Route::get('/login', 'AuthSiakad\LoginController@showLoginForm')->name('login');
Route::post('/login', 'AuthSiakad\LoginController@login')->name('login.submit');

File app\Http\Controllers\HomeController.php

<?php

namespace FKQuiz\Http\Controllers;

use Illuminate\Http\Request;

class HomeController extends Controller
{

    public function __construct()
    {
        $this->middleware('auth:siakad');
    }

    public function index()
    {
        return view('home');
    }
}

When logging in, I cannot successfully enter the Home page that is directed to LoginController.php. After I check, Auth::attempt() returns the value true but Auth::check() is false so that when entering HomeController.php, the credential entered is Auth::guest() = true. And the value Auth::user() looks like this:

UserSiakad {#229 ▼
  #connection: "pgsiakad"
  #table: "gate.sc_user"
  #hidden: array:2 [▼
    0 => "password"
    1 => "salt"
  ]
  #primaryKey: "id"
  #keyType: "int"
  +incrementing: true
  #with: []
  #withCount: []
  #perPage: 15
  +exists: true
  +wasRecentlyCreated: false
  #attributes: array:16 [▼
    "userid" => 3747
    "username" => "1522315009"
    "password" => "aa184593e6511e6d9983ba536d36cdb8"
    "hints" => "05051994"
    "salt" => "1pBAKNsSczk2aZLFAg8cgJwIpNyo7a"
    "tokenreset" => null
  ]
  #original: array:16 [▼
    "userid" => 3747
    "username" => "1522315009"
    "password" => "aa184593e6511e6d9983ba536d36cdb8"
    "hints" => "05051994"
    "salt" => "1pBAKNsSczk2aZLFAg8cgJwIpNyo7a"
    "tokenreset" => null
  ]
  #changes: []
  #casts: []
  #dates: []
  #dateFormat: null
  #appends: []
  #dispatchesEvents: []
  #observables: []
  #relations: []
  #touches: []
  +timestamps: true
  #visible: []
  #fillable: []
  #guarded: array:1 [▼
    0 => "*"
  ]
  #rememberTokenName: "remember_token"
}

I feel there is something wrong with implementing UserProvider, but I haven't managed to implement it yet. So, what is the solution? Thanks