correct product but beware of compatibility
I am a computer scientist but not a network specialist, so I made a mistake when I bought this box...
Indeed, you have to know that there are several kinds of POE adapters:
injectors on the one hand, and "splitters" on the other hand.
But above all there are several possible supply voltages for the injectors. In my case I needed a 48V injector and this product was not suitable...
That said, the LDLC after-sales service was absolutely perfect: I was able to return the product to a relay point with the labels provided by their service (thanks Emmanuelle!)
I was even refunded before the product was registered for return.