Comment No 1 Suspect: Microwave Oven (Score 1) 499
Typical Microwave ovens operate at up to 1000W @ 2.4Ghz. Typical WiFi operates at 20mW @ 2.4Ghz. Yes, a Microwave oven is shielded in a metal box but 20mW is only 1/50,000th of the power of a microwave so even the slighest noisy leak from the microwave is going to look like some serious noise to the WiFi. At my parents place, the range of the WiFi drops in half whenever the Microwave is on.