4 weeks of work and only 1 internet connection, is a legal distinction possible?

Hello,
some may still remember what we (my brother and I) are currently building. It is a semi-detached house with a total of 4 residential units.

We are currently considering, regarding the internet connection of the apartments (which are to be rented out furnished), to take only one connection and connect all other residential units to it. Technically, it is no problem for me to separate this cleanly (I will "build" a suitable router/firewall myself), but legally I am unsure how this can be arranged.

I'm not too worried, but "the devil is in the details."

I always offer customers "Freifunk routers" for legally secure guest WLANs. However, these limit the bandwidth too much.

Therefore, I would like to have a different solution here, if possible.
Fortunately, the available bandwidth is 500MBit/s (Vodafone fiber).

If this is possible, I would order the connection as a business connection (since I need one anyway with a fixed IPV4) and make it available to the others.

We are currently considering, regarding the internet connection of the apartments (to be rented out with utilities included), to only take one connection and connect all other residential units to it.

Why not rent out with utilities included but without internet? I wouldn't put myself through that hassle.

That is then the option when there is no "simple" solution for this task ;) I certainly will not put myself under stress (in the form of legal problems) because of it ... hence the question.

Hi, I wouldn't do it. We once had a shared apartment (terraced house with 4 residents in Krefeld), there was often stress because one roommate was always extremely busy downloading movies. This caused the bandwidth for the others to drop, I don't remember what kind of connection it was. The question is also: What happens if he downloads illegal stuff? Regards Olli

Why not rent without internet but with heating? I wouldn't put myself through that stress.

Meanwhile, everyone has cell phones with data plans, if they really want more, they can just order (and pay for) their own connection. Olli

How do you set up the landline connection for your tenants?