@erniel29
First - testing speedtest is nice, however, even just browsing would be sufficient. Most reports are saying that they cannot browse (See vadgito's youtube videos...). People that can browse and keep a stable connection obviously don't have the problem you are experiencing.
Second - yes there is a lot of variance in the market and as someone here already stated, that is one reason why router manufacturers are constantly working on updates. Have you verified you are using the latest firmware for the router? it is definitely worth the try...
@vadgito
Try to hard reset your Airport router. This has solved the problem for other users. The fact that it is working with other devices at this moment does not necessarily mean this is a DX problem.