UA 3871 then UA 581 at San Francisco
IAB → San Francisco → Cleveland
Timetable, San Francisco time
15:17UA 3871 from IAB at the gate
12:45UA 581 to Cleveland leaves the gate
21 h 28 apart on the timetable, overnight
UA 581 leaves 21 h 28 after UA 3871 arrives on the timetable: more than half a day, so not a connection we count.