Master’s student here, I have a national student visa for non-EU individuals, I’ve been looking up if my visa allows a change of studies. This is the only explanation in the [European Commission article for national student visa rights in Germany](https://immigration-portal.ec.europa.eu/germany-student_en) on being allowed to change studies. I don’t want to misinterpret it, does this mean I can’t begin a different program before 18 months of studying in the current one?