DL 280 then DL 438 at Seattle
Shanghai → Seattle → Boston
Timetable, Seattle time
12:00DL 280 from Shanghai at the gate
11:45DL 438 to Boston leaves the gate
23 h 45 apart on the timetable, overnight
DL 438 leaves 23 h 45 after DL 280 arrives on the timetable: more than half a day, so not a connection we count.