Why isn't my wireless operating at full speed?

The wireless signaling protocol actually has "performance degradation" built in. What that means is that if conditions aren't ideal the device can drop down to lower speeds that are less sensitive to things that might interfere.

Remember that wireless networking is, essentially, radio. When listening to the radio you might be able to tolerate some amount of static, but the quality of what you're listening to, the fidelity, suffers. If you really want the highest possible fidelity you need a strong signal with absolutely no outside noise.

The same is true of WiFi, except that the equivalent of audible 'static' on a radio is something that the wireless protocol uses to determine that it needs to slow down its transmissions in order to be clearly understood by sender and receiver.

The key to getting maximum speed is that phrase "ideal conditions".

Ideal conditions result in strong, clear signals. That means things like good antenna placement, no obstructions to interfere with the signal, no devices nearby that might be radiating electrical noise that would interfere with the signal, keeping the laptop as close to access point as possible, and so on. At the very top of the speed range, even the littlest thing like the direction the antenna or laptop is pointing, or the manufacturing quality of your specific wireless equipment might well have an impact.

Now you're probably saying to yourself "but, I don't have to do any of that, and everything seems to work ok", and you'd be quite right. Except that, as you've seen, you're not getting the full speed you might be expecting.

The wireless protocol is actually pretty robust, and manages to punch through a lot of obstacles. Just ask anyone who keeps picking up their neighbors WiFi, or the WiFi signal from the coffee house across the street. But that robustness comes at a price, and the price is typically speed.

So my advice to you is, naturally, do what's practical to give that wireless signal the best chance of getting through strong and clear from the access point to your laptop and back.

Just don't be surprised if you never see that maximum rated speed.