EI 991 then EI 3308 at Dublin
Rome → Dublin → Southampton
Timetable, Dublin time
02:00EI 991 from Rome at the gate
17:50EI 3308 to Southampton leaves the gate
15 h 50 apart on the timetable
EI 3308 leaves 15 h 50 after EI 991 arrives on the timetable: more than half a day, so not a connection we count.