The plane from Doha to Frankfurt was already delayed on departure. Then, when it approached Frankfurt, it keeps turning in circles for about another hour (apparently due to weather and congestion reasons). At some point it was was announced that the plane had to land in Stuttgart to refill the plane. Once there, we were welcome by some heavy snow showers which completely covered the plane; they had to clear it and one hour later we could take off to Frankfurt.
Since I arrived 5 hours late in Frankfurt I missed my connection to Luxembourg, but managed to catch another flight that took off 15 minutes later. And even my luggage didn’t miss the connection – bravo to the logistics in Frankfurt!