After upgrading to CM 12.1, i encountered some issues regarding LTE connectivity etc.
The Nederlands Version in one of these threads didn't help.
So I decided to go back to stock and extract my correct Baseband/Modem with the tutorial provided in an other thread.
Works like a charm now with CM 12.1. Unfortunatelly Bluetooth issues aren't fixed with it.
If someone's interested in the german baseband of a E986, I uploaded a flashable Zip.