Laravel Auth routing redirects back

I've created a project and programmed most the content locally until I've got a server. Now I have a server and I moved the files to the server. After I've got the project run normally, I've got in trouble with the authentification. ( I addet the authentification on the server, it wasn't there locally ).

Everytime I try to login or to register I only get redirected to the login/register route without any error or something like that. The DB connection works fine, I've tried getting some data of it and that worked.

I looked for the auth routes and tried to return the http header data in the register function but the programm doesn't reach this function at all.

I also tried to overwrite the register post Route in Router.php in /vendor/framework/src/Illuminate/Routing/Router.php from:

        $this->post('register', 'Auth\RegisterController@register');

to

        $this->post('register', 'TestController@test');

Just to look if in the @test function in my TestController will be reachted, but nothing. Got redirected again.

However, I haven't changed the auth controller etc. at all beside the redirect route in the login/register-controller

Here are my routes in my web.php:

Route::group(['middleware' => 'auth', 'web'], function () {
    // my routes - the user shall only see them if they are logged in
)};

Auth::routes();

If I log a user manually in, everything works fine

I really have no clue what to do anymore, does someone have a clue?

---

php artisan route:list :

via Chebli Mohamed