GQ 671 then GQ 388 at Athens
Istanbul → Athens → Thessaloniki
Timetable, Athens time
23:10GQ 671 from Istanbul at the gate
20:25GQ 388 to Thessaloniki leaves the gate
21 h 15 apart on the timetable, overnight
GQ 388 leaves 21 h 15 after GQ 671 arrives on the timetable: more than half a day, so not a connection we count.