Files not opening in browser


I installed a fresh Nextcloud according to the server manual on a Ubuntu server.
Nextcloud appears to work fine, however, the standard files that come with the installation (Nextcloud Manual.pdf or the nextcloud.mp4) are not opening in the browser (Chrome) on my laptop. Instead I get a white screen, no errors.

If I log into the files are opening fine in mij browser. Furthermore, in the mobile app on my phone files open just fine from my own Nextcloud.

Anybody got a clue?

Thank you in advance

Make sure on you app page, the the corresponding apps are enabled. If you get 500-errors or white screens, check your server logfiles (/var/log/(apache,nginx)/*) it’s very unlikely that you don’t get any errors reported.