Laravel Passport Multiauth - php

Question

I am working on an API for 2 frontend apps (vue2/mobile). One uses User model and the other uses the Admin model (Laravel is just an API)
I am using Laravel Passport for authenticating users and admins, i successfully provided access token for users but i'm facing some problem with admins
So for i did
1-> created Admin model
<?php
namespace App;
use Laravel\Passport\HasApiTokens;
use Illuminate\Notifications\Notifiable;
use Illuminate\Foundation\Auth\User as Authenticatable;
class Admin extends Authenticatable
{
use HasApiTokens, Notifiable;
/**
* The attributes that are mass assignable.
*
* #var array
*/
protected $fillable = [
'name', 'email', 'password','role',
];
/**
* The attributes that should be hidden for arrays.
*
* #var array
*/
protected $hidden = [
'password', 'remember_token',
];
}
2-> created a admins guard which uses passport
'guards' => [
'web' => [
'driver' => 'session',
'provider' => 'users',
],
'api' => [
'driver' => 'passport',
'provider' => 'users',
],
'admin' => [
'driver' => 'passport',
'provider' => 'admins',
],
],
3-> created Route and Controller for granting access token for admins
Route::post('/oauth/token/admin', [
'uses' => 'Auth\CustomAccessTokenController#issueUserToken'
]);
<?php
namespace App\Http\Controllers\Auth;
use Illuminate\Http\Request;
use Psr\Http\Message\ServerRequestInterface;
use Laravel\Passport\Http\Controllers\AccessTokenController;
class CustomAccessTokenController extends AccessTokenController
{
/**
* Hooks in before the AccessTokenController issues a token
*
*
* #param ServerRequestInterface $request
* #return mixed
*/
public function issueUserToken(ServerRequestInterface $request)
{
$httpRequest = request();
if ($httpRequest->grant_type == 'password') {
$admin = \App\Admin::where('email', $httpRequest->username)
->where('password', $httpRequest->password)
->first();
//dd($admin);
return $this->issueToken($request);
}
}
}
4-> i tested with Postman
http://localhost:8000/api/oauth/token/admin
client_id:4
client_secret:M4QkLqhPkJ4pGL52429RipassQ3BOjKTJZe3uoWK
grant_type:password
username:admin#gmail.com
password:secret
//i'm getting
{
"error": "invalid_credentials",
"message": "The user credentials were incorrect."
}
//if i use the User model credentials
username:user#gmail.com
password:secret
//i'm getting the access token
{
"token_type": "Bearer",
"expires_in": 31536000,
"access_token": "eyJ0eXAiOiJKV1Qi....",
"refresh_token": "UI354EfJlVdmOhO...."
}
i'm really tired figuring out what went wrong
looking forward for much needed help
thank you