Laying network cable

Hello,

we are currently building a townhouse with a granny flat, into which my mother will move. Since we do not need a landline phone, we want to share an internet connection.

I have little to no idea about the subject.

But I have already heard from someone that I should connect the main router in our house to the Telekom connection, then run a network cable over to the granny flat. Then the granny flat would have its own Wi-Fi and we would need a DECT phone that is connected to the main router in our house, if I understood that correctly...

Additionally, I want to run a network cable to the TV to connect it and I would like to have a Wi-Fi repeater centrally in the house (we are building with a gallery), so I think it will be enough to have a Wi-Fi repeater that is connected to the Fritzbox via a network cable. Since the Fritzbox is located in the utility room, it will not be sufficient for the entire house to every corner.

Can someone help me here with how to best set this up and what is needed for it?

I already have Cat 7 cables, which should be more future-proof ‍♂ Then first of all a flush-mounted box with empty conduit wherever I need it is clear.... And then

Thanks to "structured cabling," you can connect the outlet in the granny flat as an IP, S0, or a/b device to the "main router." The connection between the base and handset of the DECT (or cat.iq) phone then takes place via the radio link in the granny flat; I would not register the granny flat handset directly at the "main router," but use the cable route as you intend.

Regardless, I would definitely have a "real" connection installed in the [Einliegerwohnung]. Who knows who will live there someday ...

Is the [Einliegerwohnung] KFW-funded?

So the phone would then be connected to the router of the [Einliegerwohnung]? I had understood from an acquaintance that it is not possible or I misunderstood...

Regardless, I would definitely have a "real" connection installed in the granny flat. Who knows who will live there someday...

Is the granny flat funded by KfW?

No, it is not KfW. The granny flat is actually only to be rented out in an absolute emergency; otherwise, it is intended as an apartment for my mother, children, or later ourselves. It does not have a separate electricity connection either; everything will run through our house and only be sub-distributed.

Ok, then it's fine for you.

I still consider it sub-optimal, I WOULD not do it, also with regard to the (resale) value.