UA 428 then UA 1919 at Houston
Mexico City → Houston → Cozumel
Timetable, Houston time
10:09UA 428 from Mexico City at the gate
09:37UA 1919 to Cozumel leaves the gate
23 h 28 apart on the timetable, overnight
UA 1919 leaves 23 h 28 after UA 428 arrives on the timetable: more than half a day, so not a connection we count.