GQ 891 then A3 994 at Athens
Düsseldorf → Athens → Istanbul
Timetable, Athens time
21:30GQ 891 from Düsseldorf at the gate
18:30A3 994 to Istanbul leaves the gate
21 h apart on the timetable, overnight
A3 994 leaves 21 h after GQ 891 arrives on the timetable: more than half a day, so not a connection we count.