Wordpress迁移问题

I am trying to copy my wordpress website from domain http://wwww.example.nl to http://www.example.de . I have used the plugin wp-all-in-one-migrations

After some errors and changing I did the following:

1. Change home and site url in the database in wp-options
2. Disable conflicting plugins
3. Edit config.php for the right url

The database settings in wp-config are also correct and pointing to the right database with the correct settings.

But now I'm unable to login to my new domain wp-admin. Sometimes I get ERR_CONNECTION_REFUSED while trying to reach my new domain or get redirected to the old domain. But sometimes it just works right away (except for logging in)

I don't get errors ( Debug setting is set to TRUE).

How can I find out what's wrong and what direction do I go to fix this problem? If theres any more information required please let me know and I'll update my question accordingly