FR 157 then FR 340 at Dublin
Leeds → Dublin → London Luton
Timetable, Dublin time
21:55FR 157 from Leeds at the gate
14:40FR 340 to London Luton leaves the gate
16 h 45 apart on the timetable, overnight
FR 340 leaves 16 h 45 after FR 157 arrives on the timetable: more than half a day, so not a connection we count.