Android 7

SSL

There is a problem with eliptic curves, see https://code.google.com/p/android/issues/detail?id=224438

It seems to be fixed in later versions of Android 7. If possible, try to upgrade your device or use a certificate without eliptic curves. (thanks Hervé and Marcel)

Doze Mode

Some devices still seem to be affected by the doze mode bug, see Android 6