As we know, wireless signal is transmitted through the air, it can be very unstable. There are many facts may affect the transmission.
Inside a building, wall is the most common impediment that makes the signal weak. Usually, it is very hard for a wireless router to transmit three thick concrete walls.
2. Mirror and metal:
As we all, mirror can reflect the light, it can also reflect the wireless signal. Meanwhile Metal can totally block the transmission.
Please avoid such things when you place your wireless devices. If you find your wireless signal is weak and there are some places can’t be cover, you can change a place or change the direction of the antenna. Or you can consider of our Range Extenders and Powerline devices to extend the coverage.