How to Fix WiFi Interference Problems
Because radio bands are shared with other users, interference from other radio signals can affect your Mac’s WiFi’s performance. Unfortunately, if you do get interference, you are usually on your own. However, you can take steps to combat interference and other signal problems:
Move your laptop. Closer to the access point is usually better, but any change in position and orientation can help, even a few inches.
Move the access point. Put it in a more central location, hang it high on a wall, or move it away from a known source of interference, such as a cordless phone base station or a microwave oven. Experiment.
Adjust the access point’s antenna. Try small increments. If it has two antennas, have them point in different directions, at right angles to each other.
Turn off your cordless phone and unplug the base station. If that reduces the interference, move your cordless phone and base station farther from the access point and from your laptop. Plug the base station into a different outlet. If those steps don’t help, replace your cordless phone with a model that operates on a different frequency band (the band is usually marked on the package), or just go back to wired phones. (You carry a cell phone anyway.)
Get a new microwave oven. You can easily tell whether your microwave oven causes network problems — the problems only happen when it’s cooking. If the microwave is used infrequently, you might just live with the interference, but if it’s used a lot, say in a small office at lunchtime, consider buying a newer model. Also, make sure that the microwave is on a different electrical circuit from your laptops and access points.
Buy a WiFi repeater. These units plug into a wall outlet and retransmit WiFi signals from your access point for greater coverage. Having a second signal source may reduce interference problems.