OO 9909 then UA 2226 at O'Hare
Waterloo → Chicago → Buffalo
Timetable, Chicago time
16:47OO 9909 from Waterloo at the gate
14:18UA 2226 to Buffalo leaves the gate
21 h 31 apart on the timetable, overnight
UA 2226 leaves 21 h 31 after OO 9909 arrives on the timetable: more than half a day, so not a connection we count.