Answer Description
Infrared (IR) light requires line of sight in order to properly function. Infrared is most commonly used in TV remotes. WiFi, Bluetooth and Radio Frequencies (RF) do not requires LoS and can penetrate physical objects such as walls and ceilings.
Wikipedia
Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light It is therefore invisible to the human eye IR is generally understood to encompass wavelengths from the nominal red edge of the visible spectrum around 700 nanometers (frequency 430 THz), to 1 millimeter (300 GHz) (although the longer IR wavelengths are often designated rather as terahertz radiation) Black-body radiation from objects near room temperature is almost all at infrared wavelengths As a form of electromagnetic radiation, IR propagates energy and momentum, with properties corresponding to both those of a wave and of a particle, the photon
Infrared - Wikipedia, the free encyclopedia