FR 1644 then OS 643 at Vienna
Rome → Vienna → Prague
Timetable, Vienna time
20:00FR 1644 from Rome at the gate
09:25OS 643 to Prague leaves the gate
13 h 25 apart on the timetable, overnight
OS 643 leaves 13 h 25 after FR 1644 arrives on the timetable: more than half a day, so not a connection we count.