KL 1828 then KL 1653 at Schiphol
Stuttgart → Amsterdam → Firenze
Timetable, Amsterdam time
11:10KL 1828 from Stuttgart at the gate
10:25KL 1653 to Firenze leaves the gate
23 h 15 apart on the timetable, overnight
KL 1653 leaves 23 h 15 after KL 1828 arrives on the timetable: more than half a day, so not a connection we count.