UA 181 then WN 988 at Denver
Frankfurt am Main → Denver → Buffalo
Timetable, Denver time
13:40UA 181 from Frankfurt am Main at the gate
11:50WN 988 to Buffalo leaves the gate
22 h 10 apart on the timetable, overnight
WN 988 leaves 22 h 10 after UA 181 arrives on the timetable: more than half a day, so not a connection we count.