BA 841 then OS 336 at Heathrow
Dubrovnik → London → Vienna
Timetable, London time
14:15BA 841 from Dubrovnik at the gate
13:55OS 336 to Vienna leaves the gate
23 h 40 apart on the timetable, overnight
OS 336 leaves 23 h 40 after BA 841 arrives on the timetable: more than half a day, so not a connection we count.