The Duolingo cuts out after a few minutes so stops ANY progression. I am about to delete the app as it beginnig yo be a real waste of time - I have now done one minor module four times, ninety percent correctly. i am hardly getting any daily progress at all since unless I 'pay' I am told,I lose all progress. Life is too short to fight DL so I will just do Tiny Cards and correct their occasional mistakes.
You can just use the website you know? No need to pay anything so far.
Try using the PC version. It works a lot better. But that is only what I have noticed. And Have you tried Memrise?
Mine cuts out too which is why I don't use the app anymore. Just use the web browser on your phone and use Duolingo from there. It's not the best, but it works! Best wishes on your German! :-)