All kinds of things can interfere with your Wi-Fi signal and
thereby slow down your connection: fluorescent bulbs, baby monitors or even a
cheap pair of wireless headphones. This is critical for Wi-Fi performance as
only one device can use the channel at a time. In addition, Wi-FI uses CSMA-CA
to handle collisions — if it detects a collision on the channel, the Wi-Fi
device will halt sending and wait until the channel is clear. Interference
counts as collisions, so you will end up with a sporadic and halting connection
with interference nearby.
If your connection is clear, attenuation (signal drop over
distance) is a very real problem when using Wi-Fi. The 2.4 GHz band handles
attenuation better but is more subject to interference. The 5GHz band is less
subject to interference but has more issues with attenuation. Either way,
you’re still likely only to achieve speeds topping out around 600 Mbps.
If you are on the 2.4 GHz band, make sure to chose from
channels 1, 6, or 11 (or 14 if allowed by your country) — those are the only
non-colliding channels at 20 MHz. At 40 MHz, you will well consume the entire
2.4 channel spectrum, thus, it will be even more at risk of interference.
