WN 3402 then DL 821 at Atlanta
St Louis → Atlanta → Boston
Timetable, Atlanta time
19:20WN 3402 from St Louis at the gate
18:30DL 821 to Boston leaves the gate
23 h 10 apart on the timetable, overnight
DL 821 leaves 23 h 10 after WN 3402 arrives on the timetable: more than half a day, so not a connection we count.