Since around two days, login and synchronization with the android app is no longer possible. It all worked before. I now have this problem on my Android phone (Google Pixel) and on my Android tablet (Samsung). The app says I should check my internet connection. However, both devices have internet, all other apps are working.

Trouble shooting I already did:
- Reinstalled the app.
- Tried via Wi-Fi (home internet) and via mobile phone internet.
- Tried with two different VPNs (I am in Taiwan, so this shouldn't be a problem anyway).

The webpage works. I can login there, but not on the Android app.

Any ideas? I really need this app working because I am attending a Chinese intensive course right now.