But when I re-installed the host-app, I got a po-up that I had to activate Samsung Knox if I wanted to use the remote control function. I tried once not pressing on 'activate', but then I just completely couldn't connect. When I first started using Teamviewer I certainly didn't get such a pop-up, so I suppose it has indeed to do with Samsung Knox. I'm quite sure, because I now also tried connecting with my sister's smartphone (not a Samsung) and I didn't have any issue there to access apps.