DL 706 then DL 518 at Atlanta
Denver → Atlanta → Boston
Timetable, Atlanta time
18:01DL 706 from Denver at the gate
16:25DL 518 to Boston leaves the gate
22 h 24 apart on the timetable, overnight
DL 518 leaves 22 h 24 after DL 706 arrives on the timetable: more than half a day, so not a connection we count.