UA 3913 then UA 348 at Houston
Denver → Houston → Miami
Timetable, Houston time
21:22UA 3913 from Denver at the gate
14:45UA 348 to Miami leaves the gate
17 h 23 apart on the timetable, overnight
UA 348 leaves 17 h 23 after UA 3913 arrives on the timetable: more than half a day, so not a connection we count.