AC 4121 then UA 817 at San Francisco
Ontario → San Francisco → Mexico City
Timetable, San Francisco time
17:50AC 4121 from Ontario at the gatealso UA 5483
13:14UA 817 to Mexico City leaves the gatealso AC 5402, NH 7368, NZ 9823
19 h 24 apart on the timetable, overnight
UA 817 leaves 19 h 24 after AC 4121 arrives on the timetable: more than half a day, so not a connection we count.