FTTH/Network/DECT/IPTV is it correct?

The Gigaset Pros are, to my knowledge, IP-based. They belong to a LAN port. It also makes sense, as you can place the base where you need it. In combination with a Gigaset repeater, you get the best DECT coverage with full functionality. I actually decided against the Pro only because it is not fully compatible with the "normal" Gigaset mobiles, but you have to use the "Pro" mobiles accordingly. We now have an S810A and our old SL910 in combination with full compatibility. Address book, answering machine, everything from one source. Works great. And no DECT reception problems, because the base has to be at the house connection. Plus the Canon MX925 in the office at the LAN socket as fax on the router as an analog device. Works perfectly.

The N510 IP Pro DECT base does not have an RJ11 connection. It is connected via LAN. Therefore, I thought I had to bring the phone signal from the FritzBox into the network via the RJ11/RJ45 cable and then pick it up again on the ground floor. What would be the correct procedure to connect the DECT base on the ground floor?

IP phones (including the mentioned DECT bases) have absolutely NOTHING to do with any telephone signals or telephone connections. It all runs entirely over LAN. In the FritzBox, you simply set it up as an IP phone and off you go. Forget about the telephone connection on the FritzBox once and for all; today, at most, only a fax needs it, and even then, it’s better to use an external ATA.

I would first try to see if the DECT signal of the Fritzbox is already sufficient. The advantage would be that you don't have to integrate an additional device into your infrastructure and can manage more in the (in my opinion well-designed) Fritzbox, including the phonebook. If it doesn't work, you can always buy the Gigaset later.

We use it exactly like this in our house (with reinforced concrete ceilings): the Fritzbox is in a 19" rack in the basement and telephony via DECT still works perfectly in the attic. This may not apply to every house, but it’s worth a try.

In addition, AVM also offers their Fritzfon app, which allows you to make calls via the smartphone and the home WLAN. I now use this almost exclusively because my smartphone is basically always with me and we also have first-class coverage with three access points.

Thank you for the input. Since we are on the topic of access points, where should the APs ideally be positioned?

IP phones (including the mentioned DECT bases) have absolutely NOTHING to do with any telephone signals or telephone connections. Everything runs completely over LAN. In the FritzBox, you simply set it up as an IP phone and off you go. Forget about the telephone connection on the FritzBox; today, at most, only a fax needs it, and even then, it's better to use an external ATA.

Thank you for the hints. I had misunderstood. Only if I want to bring the analog signal to a specific network socket, do I connect the FritzBox directly to the patch panel with the RJ11/RJ45 cable and then connect the analog phone to the corresponding socket. Correct? Otherwise, as you wrote, plug in and off you go.

Aps should be placed where you need the most speed / usage.
So for example living room/technology/children's room...