EW 752 then OS 771 at Vienna
Cologne → Vienna → Sofia
Timetable, Vienna time
09:30EW 752 from Cologne at the gate
09:20OS 771 to Sofia leaves the gate
23 h 50 apart on the timetable, overnight
OS 771 leaves 23 h 50 after EW 752 arrives on the timetable: more than half a day, so not a connection we count.