App page does not load

Nextcloud version: 12.0.3
Operating system and version Ubuntu 16.04.3
Apache or nginx version: Apache 2.4.18
PHP version: 7.0

Hi everybody,

When i try to go to the app page in my admin account the page will be loading for a long time and in the end show nothing except the menu. My log shows

13T08:41:28+00:00”,“remoteAddr”:“”,“user”:“nextcloud”,“app”:“appstoreFetcher”,“method”:“GET”,“url”:"/nextcloud/index.php/settings/apps/list?category=installed",“message”:“Exception: {“Exception”:“GuzzleHttp\\Exception\\ConnectException”,“Message”:“cURL error 28: Connection timed out after 10000 milliseconds”,“Code”:0,“Trace”:”#0 \/var\//www\/nextcloud\/3rdparty\/guzzlehttp\/guzzle\/src\/RequestFsm.php(103): GuzzleHttp\\Exception\\RequestException::wrapException(Object(GuzzleHttp\\Message\\Request), Object(GuzzleHttp\\Ring\\Exception\\ConnectException))\n#1 … and so on

I already tried adding
’appstoreenabled’ => true,
’appstoreurl’ => ‘

to my config file.

The server was behind a proxy. Fixed this by adding ‘proxy’ => ‘address:port’ to the config file