UA 3902 then UA 417 at Houston
Toronto → Houston → Los Angeles
Timetable, Houston time
08:27UA 3902 from Toronto at the gate
06:10UA 417 to Los Angeles leaves the gate
21 h 43 apart on the timetable, overnight
UA 417 leaves 21 h 43 after UA 3902 arrives on the timetable: more than half a day, so not a connection we count.