Number of network sockets; how to plan Wi-Fi in the new building?

These are protective tubes.

The offer, however, states empty conduit. I also believe that the electrician on site spoke of empty conduits. The non-exchangeability therefore confused me as well. I will clarify this again otherwise.

Whatever pipe he uses. Interchangeability should be ensured. Because that is also the purpose of the matter in addition to mechanical protection.

In practice, hardly any cable is truly replaceable. Bending angles would have to be maintained that are simply hardly feasible in a single-family house. Every electrician you ask will really tell you that. You might still get a short cable exchanged by luck, but as soon as it involves several corners, it won’t work anymore. Apart from that, anyone who now has Cat7 or Cat8 in the wall will never change a cable during their lifetime.

In practice, hardly any cable is truly interchangeable. Bending angles would have to be observed that are simply hardly feasible in a single-family house. Every electrician you ask will tell you the same. With luck, you can still replace a short cable, but as soon as it involves several corners, that's no longer possible. Aside from that, anyone who now has Cat7 or Cat8 in the wall will not replace the cable again in their lifetime.

That’s exactly how I understood the electrician as well. That means the empty conduit then only functions as a protective pipe after all, and inspecting the rough installation makes sense before the cables disappear into the screed.

Our electrician told me the same. That he doesn't provide any warranty if I only have empty conduits installed. I wonder what the warranty is good for if the installers can't get through the conduit anyway... In my opinion, it's a bit of a scare tactic so that you end up spending the 100€ per network connection because it actually works. But I'm happy to take the risk now, I spend a bit more time on the construction site and, if necessary, lay a network cable again if the route looks too winding to me. I just did that for the ground floor ceiling last Friday. No problem and it doesn't bother the installers at all.

If you have trouble getting cables through, you can either take a small piece of styrofoam, light packaging material, or similar, tie it to a thin string. Then stick it into one end of the empty conduit and hold a strong vacuum cleaner at the other end. Alternatively, Runprotec offers a pulling aid called Runpotec Runpo, which supposedly makes it much easier to get through an empty conduit than with some DIY store wire. However, it costs a few euros but pays off after a certain number of empty conduits.