UA 1720 then DL 2709 at Houston
Denver → Houston → Atlanta
Timetable, Houston time
11:14UA 1720 from Denver at the gate
08:05DL 2709 to Atlanta leaves the gate
20 h 51 apart on the timetable, overnight
DL 2709 leaves 20 h 51 after UA 1720 arrives on the timetable: more than half a day, so not a connection we count.