UA 3905 then UA 534 at Houston
Cancún → Houston → Denver
Timetable, Houston time
13:29UA 3905 from Cancún at the gate
08:30UA 534 to Denver leaves the gate
19 h 01 apart on the timetable, overnight
UA 534 leaves 19 h 01 after UA 3905 arrives on the timetable: more than half a day, so not a connection we count.