Update WordPress after first install

I can not automatically update to 4.4.2 after initially installing the $wp_version = ‘4.3.3’;

I was able to update the plugins and templates, but not the WordPress version itself.
The program is installed on my own NAS – Synology DS211j into the sub-directory WordPress of the web directory -“\web\wordpress”. The User has admin rights for the root and all sub-folders.

Thank you in advance for your response!