JU 8510 then UA 796 at San Francisco
New York JFK → San Francisco → Boston
Timetable, San Francisco time
23:54JU 8510 from New York JFK at the gate
21:30UA 796 to Boston leaves the gatealso VA 8308, NZ 9012
21 h 36 apart on the timetable, overnight
UA 796 leaves 21 h 36 after JU 8510 arrives on the timetable: more than half a day, so not a connection we count.