WiFi
WiFi's reliability presents a curious paradox. On paper, the technology is a marvel of engineering: radio waves propagating at the speed of light, carrying data through walls, around corners, and occasionally through the neighbours' interference. Modern routers operate continuously for years without conscious thought from their owners.
In practice, however, WiFi has cultivated a reputation for selective abandonment. It performs flawlessly during idle browsing, then mysteriously fails during crucial video conferences. It provides robust connectivity throughout the house except in the one room where one actually needs to work. Router placement has become a dark art, discussed in hushed tones by those who've suffered.
The technology's reliability is best described as 'usually excellent, catastrophically absent at the worst possible moment.' This characteristic has spawned an entire industry of WiFi extenders, mesh networks, and router upgrades - proof that reliability remains a work in progress.