JackMDS has done a great job with ezlan.net
But there are some fundamentals about WiFi that need to be stickied that don't pertain to products and would help everybody. This only pertains to 2.4 Ghz wireless.
1) Change channels to 1, 6, 11 to see what works best - this solves most problems. You can download netstumbler to see what is in your area but really what channel is a "try to see what works best for you". Apartments or other close living quarters can be problematic.
2) Eliminate interference - phones, bluetooth, microwaves. Keep them away from senders and receivers. The farther you have these devices from you router and clients the better.
3) Don't "point" antennas at each other, that is the lowest strength there is in an omni-directional antenna. Imagine a doughnut as your antenna, the shape of the doughnut is your signal. The "hole" of the doughnut is where it is the worst, if you point these holes at each other even the best wireless gear out there will not perform very well. If your antennas are like this "AP- -client" that is the worst you can get. If your antennas are like this "AP| |client" that is the best you can get. This applies to any omnidirectional antenna (every antenna on a SOHO wireless device), any other type of specialty purpose antenna you can ignore it.
4) Broadcast the SSID - there is no security in not doing this and best practice is to broadcast it because many clients have problems if it is not.
And lastly - if you have a noisy environment with other wireless devices or interference within a 100 meters...you're going to have trouble. Trouble is very poor performance, frequent disconnects, you are "connected" but can't really communicate reliably and general "it's not working all the time and most of the time it's really slow".
If you are indeed in an environment with other 2.4 Ghz close to you there may not be a lot you can do after changing channels. If this is the case then look to 5 Ghz wireless, but the principles of antenna placement/positioning still apply. Even though 5 Ghz loses more signal through dense material the result can still be MUCH better than a noisy 2.4 Ghz environment.
-edit-
Edited for clarity.
But there are some fundamentals about WiFi that need to be stickied that don't pertain to products and would help everybody. This only pertains to 2.4 Ghz wireless.
1) Change channels to 1, 6, 11 to see what works best - this solves most problems. You can download netstumbler to see what is in your area but really what channel is a "try to see what works best for you". Apartments or other close living quarters can be problematic.
2) Eliminate interference - phones, bluetooth, microwaves. Keep them away from senders and receivers. The farther you have these devices from you router and clients the better.
3) Don't "point" antennas at each other, that is the lowest strength there is in an omni-directional antenna. Imagine a doughnut as your antenna, the shape of the doughnut is your signal. The "hole" of the doughnut is where it is the worst, if you point these holes at each other even the best wireless gear out there will not perform very well. If your antennas are like this "AP- -client" that is the worst you can get. If your antennas are like this "AP| |client" that is the best you can get. This applies to any omnidirectional antenna (every antenna on a SOHO wireless device), any other type of specialty purpose antenna you can ignore it.
4) Broadcast the SSID - there is no security in not doing this and best practice is to broadcast it because many clients have problems if it is not.
And lastly - if you have a noisy environment with other wireless devices or interference within a 100 meters...you're going to have trouble. Trouble is very poor performance, frequent disconnects, you are "connected" but can't really communicate reliably and general "it's not working all the time and most of the time it's really slow".
If you are indeed in an environment with other 2.4 Ghz close to you there may not be a lot you can do after changing channels. If this is the case then look to 5 Ghz wireless, but the principles of antenna placement/positioning still apply. Even though 5 Ghz loses more signal through dense material the result can still be MUCH better than a noisy 2.4 Ghz environment.
-edit-
Edited for clarity.