Mounting a hanging shelf - Metal everywhere in the wall?

Good day,

I need your advice once again.

I would like to hang a wall shelf. Now I have bought a Bosch Multi-Detector. However, it shows on at least 50% of the wall, and especially in the area where the shelf is actually supposed to be mounted, that there are metal/pipes/cables (i.e. yellow/red light on the detector), in any case something metallic, in the wall. The wall separates the living room from the bathroom (bathtub and washing machine connection), above us lives another party. The shelf is to be mounted at a height of about 1.70m. In the lower area there are several sockets, but based on internet research I assume that these probably run towards the floor.

Unfortunately, the landlord does not have a building plan. Can/should I therefore better drop the matter? Or should I perhaps consult a professional? What would you do?

Best regards
bpe

Massive wall or drywall?

I would say massive wall, sounds like that when knocking. Regards

Does anyone perhaps have a tip? Otherwise, I would refrain from it. Or is it worth consulting a specialist there? To whom would one turn in that case? Thanks and regards

On which side is the shelf supposed to be built? The detector is garbage that shows signals everywhere in my new building, even though it is a pure KS wall and there are no cables running there.

Well, on another wall it glows green except in the area of the light switch. So at first glance the device seems reliable to me.

The shelf is to be hung in the living room.

Regards, bpe