UA 3905 then DL 1216 at Houston
Cancún → Houston → Los Angeles
Timetable, Houston time
13:29UA 3905 from Cancún at the gate
07:00DL 1216 to Los Angeles leaves the gate
17 h 31 apart on the timetable, overnight
DL 1216 leaves 17 h 31 after UA 3905 arrives on the timetable: more than half a day, so not a connection we count.