I think you can stay longer if your position is paid for by a private party instead of publicly funded. That could very well be the case at an institute. Maybe

I think you can stay longer if your position is paid for by a private party instead of publicly funded. That could very well be the case at an institute. Maybe reach out to them, best a professor and explain your situation. Link in german: https://www.forschung-und-lehre.de/die-zehn-haeufigsten-irrtuemer-ueber-das-wisszeitvg-677/ https://www.forschung-und-lehre.de/die-zehn-haeufigsten-irrt... Nr 3