B6 393 then DL 3876 at Denver
Boston → Denver → Austin
Timetable, Denver time
11:47B6 393 from Boston at the gate
09:42DL 3876 to Austin leaves the gate
21 h 55 apart on the timetable, overnight
DL 3876 leaves 21 h 55 after B6 393 arrives on the timetable: more than half a day, so not a connection we count.