Hi Daniel,
open: no end to end connection. Wire broken/plug or socket badly crimped. "Unterbrechung" in german.
short: shortcut or "Kurzschluss" in german.
May be, there is another status keyword for overlength. Don't know.
Since on pair of wires is unusable, port falls back to 100 Mbit/s. 1 Gbit/s woul require all wires to be ok.
From the lenght values:
Cable is 71 m long, measured from socket -outlet of switch to socket-outlet of AP.
Error on wire pair 3-6 is in a distance of 63 m away from socket-outlet of switch.
Since length measurement has an accuracy of +/- 5 m (according to manual), I'd expect the error at wall-outlet near AP.
Maybe you can use a different cable? Otherwise I recommend cable measurement with cat6/7 analyzer to further locate/isolate the error.
Regards, Jö