What Causes Wi-Fi Black Spots?
WiFi black spots can be caused by three things: interference, physical obstruction, and distance, sometimes separately, sometimes at the same time, with one factor aggravating the other.
Interference is, quite simply, a disturbance caused by other devices which emit radio signals in the same frequency band used by your Wi-Fi network. This causes the Wi-Fi signal to be “lost” amid all the “noise”. Wi-Fi black spots occur in areas where interference is severe enough that a phone or laptop simply can’t “keep talking” to the Wi-Fi access point well enough to maintain a connection – or, indeed, even to connect.
It’s exactly the same mechanism that makes it hard to talk to somebody in a noisy pub: even if they’re speaking clearly and you are close enough to each other, sometimes there’s just too much noise for you to understand what they’re saying.
Physical obstruction is a little less obvious because of how EM waves behave, but the name gives it away: Some areas may simply not be covered by a Wi-Fi access point. Wi-Fi black spots occur in areas where the signal simply isn’t strong enough to be picked up, even in the absence of interference.