Bauhaus concrete villa with core insulation - experiences

There are even 17 pieces

Do they multiply

Yes I switched outside from the Mesh pro to Flex HD in two places. Only at the back does the Mesh pro remain. I can't see it there. The Mesh pro are now being used in the technical rooms. But they are only activated when needed.

Are there any disadvantages to mounting APs on the wall instead of the ceiling?

The "Ufos" are actually intended for ceiling installation. Wall APs have a different radiation pattern. With a well-placed ceiling AP you irradiate the room homogeneously, whereas with wall mounting you have a strong signal close to the access point and a weaker one on the other side of the room... If you then place furniture in front of it, it gets even worse. If you put it in the line of sight, you might as well place it optimally on the ceiling.

Drywall is not good for wifi. Therefore, better not invisible under the ceiling!