Why is my Wifi connection slower than ethernet even though bandwidth should saturated?

Question

I'm wondering why it is that my wireless connection is slower than my wired connection for things going to the outside world (so, not files being transferred within the network), which is should be faster than the outside connection, which, I would think, would mean that downloading something like an ISO or other large file from the Internet should be the same either way since that should saturate the connection anyway.

Does it have something to do with the encryption (WPA)?

Could it have something to do with MTU since the MTU for ethernet can be in the range of 1500 to 9000 bytes, and 2304 bytes for 802.11?

Do wireless packets have to be buffered, whereas this wouldn't be an issue with ethernet?

What's the math behind the difference?

Answer 1

Latency

Internet connection speed is a made up by a combination of bandwidth and latency. That's the reason why large organisations will spread servers all across the country/world. By limiting the number of hops they can guarantee that the data gets to you quicker with fewer data collisions along the way (that require some packets to be re-sent).

In the realm of home networking think about Ethernet vs Wireless. In ethernet the signals are already converted to the format used by 802.3 networks when they come through the gateway. To send them down the line they are buffered and piped through to their specified destination with little or no signal or packet loss due to the direct wired connection and simple infrastructure.

With wireless 802.11 the signal needs to be converted to the correct format by attaching wireless specific info to the packet, then the packet needs to be converted to a wireless format that can be transferred. Factor in wireless interference and the fact that a lot of packets will be corrupted along the way due to the frail nature of radio transmissions and the high factor of interference; and you have a lot of packets that'll need to be re-transmitted.

All of those factors add increase the latency of the data transfer. Even though the distances of travel are trivial, the additional complexities that make wireless 'work' will inevitably increase the latency.

If you had top-of-the-line equipment and you lived in a radio vacuum you may be able to get WiFi latency that comes close to ethernet but... In a realistic environment, a little occasional lag is the best you can hope for.

There are certain settings you can tweak on a wireless to attempt to improve the connection quality but, with everybody running personal wireless routers in close proximity, there's bound to be a lot of interference.

Answer 2

Do not believe the connection speed that you see in connection properties.

This is down to many factors and it can be anything from range, interference and the quality of your infrastructure - e.g. Do not expect a £20 unbranded router to provide the same speed as a £500+ Cisco Wireless Access Point.

You may also want to try editing the MTU and other settings (At your own risk!) as you said. but a lesser action can simply be to update your drivers/

This is a very awkward issue, but I would say that the main problem comes down to the quality of the hardware and driver - e.g. a few laptop manufacturers use the cheapest wireless cards and don't even plug in all the aerial ports.

Answer 3

WIFI is also half duplex, unless the devices on both ends use one channel to transmit and one to receive.

Answer 4

WiFi can be slowed down by interference or bad reception.
Try to change the channel to 11, which is the strongest, and see if there's an improvement.

Also, a router with MIMO technology may be faster.