This is pretty fascinating between the crappy instructions from Aeotec and the European wiring!
Now, the principle behind a regular 3-way switch is that there is always hot going through one of the travelers. If you think about it, all you’re really doing is mirroring 2 single-pole/double throw switches to each other.
But I think the premise behind this switch is that you move the hot side control completely to the nano switch for the load output and the wall switches are just a normally open/closed toggle on whether the “out” terminal sends power to your light or not.
It also would seem as if the 2nd switch is completely superfluous as well. I’d be testing that thing left and right with a meter just to understand the darned thing!
Anyway, all my rambling aside, seems as if someone encountered this and got some help directly from Aeotec (Aeotec nano switch DTH?).