GQ 681 then TK 1850 at Athens
Sofia → Athens → Istanbul
Timetable, Athens time
21:55GQ 681 from Sofia at the gate
15:45TK 1850 to Istanbul leaves the gate
17 h 50 apart on the timetable, overnight
TK 1850 leaves 17 h 50 after GQ 681 arrives on the timetable: more than half a day, so not a connection we count.