I have the box also for rent by KabelDeutschalnd (that's the only thing that annoys me that you can not buy the unit - but I knew that before). I wanted to again have a Fritz! Box, and this (as well as the date) has not disappointed me:! Me easy handling, light + comfortable furniture on the computer. Surely it supports sometimes - but with Fritz box previously hinbekommen everything!.
Whether the box has particularly good specifications / features such as coverage I can not judge, but for me also WLAN / DECT works to the top floor (the box is on the ground floor of a Bauhaus light, use is both there and one floor up).
I do not understand here also some: sure is a pity that man can not buy the device (KD), but that the box is only for rent is clearly visible on the HP of KD. Thus one is always risk, whether a "foreign" device works (here probably from techn. Reasons)
In short: I am satisfied and agree with the comment from 02:08:13
Addendum: The registration / deployment of the printer over Wi-Fi / LAN for desktop + laptop worked quickly and (almost) without any problems.