AC 4121 then UA 2837 at San Francisco
Ontario → San Francisco → Washington
Timetable, San Francisco time
10:55AC 4121 from Ontario at the gate
23:20UA 2837 to Washington leaves the gate
12 h 25 apart on the timetable
UA 2837 leaves 12 h 25 after AC 4121 arrives on the timetable: more than half a day, so not a connection we count.