FR 1644 then OS 775 at Vienna
Rome → Vienna → Sofia
Timetable, Vienna time
21:30FR 1644 from Rome at the gate
15:30OS 775 to Sofia leaves the gate
18 h apart on the timetable, overnight
OS 775 leaves 18 h after FR 1644 arrives on the timetable: more than half a day, so not a connection we count.