UA 671 then DL 3876 at Denver
Jacksonville → Denver → Austin
Timetable, Denver time
10:02UA 671 from Jacksonville at the gate
09:42DL 3876 to Austin leaves the gate
23 h 40 apart on the timetable, overnight
DL 3876 leaves 23 h 40 after UA 671 arrives on the timetable: more than half a day, so not a connection we count.