FR 338 then FR 156 at Dublin
London Luton → Dublin → Leeds
Timetable, Dublin time
20:55FR 338 from London Luton at the gate
14:55FR 156 to Leeds leaves the gate
18 h apart on the timetable, overnight
FR 156 leaves 18 h after FR 338 arrives on the timetable: more than half a day, so not a connection we count.