Connect from mobile phone error: "server installation not found"

Please help us by providing the following info.

Steps to reproduce
1.downloaded owncloud app over play store
2. tested own cloud from computer - works fine
3. trying to connect Phone to Own Cloud says "Server installation not found"

Expected behaviour
Tell us what should happen
phone should connect :slight_smile:
connection from computer works fine
Actual behaviour
Tell us what happens instead
Phone Says "Server installation not found" no matter if i try http or https
Mobile client configuration
Client OS (iOS, Android, ...):
Client version: tried on tablet (galaxy tab 10.2 runing some older android version) and phone one plus 2 (android 6)

Server configuration
Operating system: Zyxel NAS 542, don't know excactly
Web server:
PHP version:
ownCloud version (see ownCloud admin page): 7.0.2
Updated from an older ownCloud or fresh install: fresh installed over zyxel pakage
ownCloud log (data/owncloud.log):

Special configurations (external storage, external authentication, reverse proxy, server-side-encryption):

ownCloud version (see ownCloud admin page): 7.0.2

Please update to a recent version of ownCloud from (at minimum 8.0.14).

No support for such an outdated version like 7.0.2 (except upgrading help) can be given here.