DL 175 then DL 543 at Atlanta
Milan → Atlanta → St Louis
Timetable, Atlanta time
17:45DL 175 from Milan at the gate
15:45DL 543 to St Louis leaves the gate
22 h apart on the timetable, overnight
DL 543 leaves 22 h after DL 175 arrives on the timetable: more than half a day, so not a connection we count.