Calender and contacts missing in NC 11.0.2 (stable)

I just installed a fresh Nextcloud 11.0.2 on an odroid C2 running Armbian/Debian 3.14.79, PHP 7.0.16-3, Apache/2.4.25 (Debian) and MySQL 5.0.12.

Sadly there is no option to enable/activate the contacts and calendar apps.

On https://docs.nextcloud.com/server/11/user_manual/pim/contacts.html I can just read "The Contacts app is not enabled by default in Nextcloud 11 and needs to be enabled separately. … 11 replace:: 11"
The problem is that its not showing at the admin panel.

But on the live Demo from Nextcloud there are several more categories at the app panel and I can see contacts and calendar.

I already tried to add this to the config:
‘appstoreenabled’ => true,
‘appstoreurl’ => ‘https://api.nextcloud.com/v1’,

Restarted the apache service and the system but I had no luck.

Can you tell me what the problem is?

You don’t have a firewall in place that could block the internet connection of the server?

Worst case: you can always download an app manually from apps.nextcloud.com and extract it in the apps/-folder. The folder-name of the app should be identical to the app-name.