UA 1599 then UA 3754 at Houston
Denver → Houston → Waco
Timetable, Houston time
15:08UA 1599 from Denver at the gate
11:30UA 3754 to Waco leaves the gate
20 h 22 apart on the timetable, overnight
UA 3754 leaves 20 h 22 after UA 1599 arrives on the timetable: more than half a day, so not a connection we count.