B6 1254 then DL 5679 at Boston
Washington National → Boston → Louisville
Timetable, Boston time
15:00B6 1254 from Washington National at the gate
09:55DL 5679 to Louisville leaves the gate
18 h 55 apart on the timetable, overnight
DL 5679 leaves 18 h 55 after B6 1254 arrives on the timetable: more than half a day, so not a connection we count.