FR 3881 then FR 332 at Dublin
Dubrovnik → Dublin → London Luton
Timetable, Dublin time
23:05FR 3881 from Dubrovnik at the gate
16:05FR 332 to London Luton leaves the gate
17 h apart on the timetable, overnight
FR 332 leaves 17 h after FR 3881 arrives on the timetable: more than half a day, so not a connection we count.