Yes, WiFi signals can generally pass through walls and other solid objects, although the strength of the signal may be reduced depending on the thickness and composition of the wall. WiFi signals are electromagnetic waves, which are a type of energy that can travel through a vacuum (such as outer space) or through various materials, including air, water, and solid objects. However, certain materials, such as metal or concrete walls, can block or weaken WiFi signals by reflecting or absorbing the electromagnetic waves. The ability of WiFi signals to pass through walls and other objects can be useful, but it can also cause interference and other issues if not properly managed.  Generally speaking it is best to expect WiFi will work most optimally in the room where the WiFi Router is located.