UA 6203 then LN 744 at Dulles
Charlotte → Washington → Buffalo
Timetable, Washington time
16:35UA 6203 from Charlotte at the gate
13:01LN 744 to Buffalo leaves the gate
20 h 26 apart on the timetable, overnight
LN 744 leaves 20 h 26 after UA 6203 arrives on the timetable: more than half a day, so not a connection we count.