Very secure thanks to frequency-hopping spread spectrum (FHSS) technology and limited range. Of course, even here there is no 100% security, but a hacker would have to be in the immediate vicinity of the radio and try to intercept the signal with special equipment and cannot try to crack the internet connection from anywhere in the world.
This has never happened to me. I have had the camera for 2 years and I am happy with the product. The only negative thing is that after a while the camera battery doesn't hold so much.
It depends mainly on how much conductive material is in the wall. I think the transmission power is sufficient, after all, in our case the signal reaches about 15 m through three interior walls and the exterior wall, or about 15 m through an interior wall, a thick concrete floor and another interior wall into the laundry room. We live in a rented flat, new building.
Keep in mind that the higher the transmission power, the higher the radiation exposure of the baby monitor.
In my opinion, there are also baby monitors that can transmit directly to the mobile phone via WLan. With this, you could amplify the signal outside the children's room with a repeater so that you have sufficient reception in the garden.
If you want to know exactly, you may find the answer here: PDF of a PowerPoint presentation "Electromagnetic waves in matter" from the University of Kassel --> https://www.uni-kassel.de/fb10/fileadmin/datas/fb10/physik/oberflaechenphysik/exp2/Lehre/ExpPhysII/Wellen-in-Materie.pdf
Due to the Corona situation, there are delivery delays and supply bottlenecks. Unfortunately, this is not over yet. The current estimated delivery time is two months. However, this cannot be guaranteed due to the above-mentioned situation (information without guarantee).
I find the speech function in particular soooo terrible.... Lullabies, on the other hand, I find ok... But also worlds off, considering where the technology is today.... My baby would wake right up if I used the talk function.... Because it sounds like a robot.... There really needs to be something new on the market...
According to our own research, it is not possible to connect a second monitor to this model. You would have to buy a completely new set. However, you have to take care that it is a digital device and that the two devices do not transmit on the same frequency and can therefore interfere with each other. It is recommended to use a different model than the existing one, but it does not matter if it is from the same manufacturer, because the different models do not transmit on the same frequency.