Site Redirecting to wp-signup.php

Hi There,

I'm new here and got a problem with my multisite WP page.
My hosting provider just moved my newly developed website from my testing domain to the definitive domain. But now my site url say's And I don't see the page.

I've been searching on this problem and that's what brought me to your company. I did find these two pages and about the same topic. However I've tried the solutions, but they didn't solve my problem.

I now got this in my wp-config
define('WP_DEBUG', false);
define( 'WP_ALLOW_MULTISITE', true );
define('MULTISITE', true);
define('SUBDOMAIN_INSTALL', true);
define('DOMAIN_CURRENT_SITE', '');
define('PATH_CURRENT_SITE', '/');
define('SITE_ID_CURRENT_SITE', 1);
define('BLOG_ID_CURRENT_SITE', 2);
define( 'NOBLOGREDIRECT', '' );

But as a result the page says that there is a problem loading the page and Firefox says the server request is redirected in a way that will never end. A problem that can be caused by disallowing cookies (Sorry, this is my translation from Dutch.)

I hope you can help me solve this issue. Thanks in advance!