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 radiation (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light It is therefore generally invisible to the human eye, although IR at wavelengths up to 1050 nanometers (nm)s from specially pulsed lasers can be seen by humans under certain conditions IR wavelengths extend from the nominal red edge of the visible spectrum at 700 nanometers (frequency 430 THz), to 1 millimeter (300 GHz) Most of the thermal radiation emitted by objects near room temperature is infrared As with all EMR, IR carries radiant energy and behaves both like a wave and like its quantum particle, the photon
Infrared - Wikipedia, the free encyclopedia