Fluctuation in web speed

[rlj89]

So I've noticed fluctuations in my web speed over the past 5-6 months when streaming media and downloading files. When plugging in an ethernet cable the problem is instantly fixed.

I'm no brainiac when it comes to networking, so I thought I would give you a walkthrough of my home setup, and hopefully one of you pro guys can give me a hint as to what is causing my problems.
And just to emphasize - by fluctuations I mean from max download speed (haven't noticed any as for upload speed) to below max (varying in severity):

From my danish wall I have a cable going to my router, which has been given to me by my internet provider 2 years ago. The router is then wired by ethernet to an airport express, which is the item transmitting our wireless signal to my 3 soon to be 4 year old iMac running the latest OSX.

Some of the information given might be needed, some might be somewhat out of place. As stated I am by any stretch of the imagination not an 'informed' individual when it comes to networking.

Thanks alot!
Rune

 

[bill001g]

Its the key issue with wireless and why you want to avoid it if you don't absolutely have to use it.

Wireless is susceptible to interference. It could be cordless phones,the neighbors wireless, microwave or it can be as simple as a second machine in your own house just getting unlucky and transmitting at the same time. Only a single device including the router may transmit at one time, if multiple try everyone must try again.

Anytime you get packets damaged the wireless needs to retransmit the data which causes what appear to be delays and slowness. Its just one of those things you learn to live with or avoid by using cables.