GQ 391 then TK 1848 at Athens
Thessaloniki → Athens → Istanbul
Timetable, Athens time
08:25GQ 391 from Thessaloniki at the gate
06:55TK 1848 to Istanbul leaves the gate
22 h 30 apart on the timetable, overnight
TK 1848 leaves 22 h 30 after GQ 391 arrives on the timetable: more than half a day, so not a connection we count.