FR 44 then OS 823 at Vienna
Athens → Vienna → Thessaloniki
Timetable, Vienna time
17:25FR 44 from Athens at the gate
12:30OS 823 to Thessaloniki leaves the gate
19 h 05 apart on the timetable, overnight
OS 823 leaves 19 h 05 after FR 44 arrives on the timetable: more than half a day, so not a connection we count.