Hello, a big reason is that the walls of the house have a lot of rebar inside, plus if there is a metal security window will play a big role in shielding the signal. Furthermore, wireless communication relies on the propagation of electromagnetic waves to establish communication links, the nature of the wave, the construction of a particular house type may increase the wall, the ground to the wave reflection, thus interfering with the signal, but this point has a very small impact. Suggest that you can buy a signal booster on TAO treasure, I myself before living in the 2nd floor there is no signal, and then bought a, the results of 4G signal at home can also be used. I hope you can help, hope to adopt!