U2 803 then U2 825 at Gatwick
Edinburgh → London → Belfast International
Timetable, London time
15:15U2 803 from Edinburgh at the gate
12:15U2 825 to Belfast International leaves the gate
21 h apart on the timetable, overnight
U2 825 leaves 21 h after U2 803 arrives on the timetable: more than half a day, so not a connection we count.