Most of the people voting for the AFD are just upset with the current political Partys

Maybe some, but several studies have shown, that a good deal of AfD voters are in fact completely on board with their fascist world view.
And those who are not still tolerate it.

Just blaming it all on dissatisfaction without addressing the deep seated bigotry in large parts of the population does not help the discussion and in imho only helps to further legitimize the AfD as a serious alternative.