display method issue

Hello
I have following issue. I've created new controller and added index($id) method with the parameter $id, But I receive an 404_error when I try to open the url localhost/subscription/111
This url works correctly localhost/subscription/index/111
When I remove parameter from the method, the method also works well, but I have to use this url localhost/subscription/111 instead of localhost/subscription/index/111
Could you advise how to resolve this issue?
here is my code:

PHP Code:

class Subscription extends ClientsController
{
    public function __construct() {
        parent::__construct();
    }
    public function index( $id ) { 


PHP Code:

        echo $id;
    }
} 


Hi,
Share the Config/Routes.php code.

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Hi,
Share the Config/Routes.php code.

thank you for the assistment, I've  checked the Config/Routes.php and added new route there.