WIFI Slow on Devices

[Pictureperfect]

I just got my ADSL installed and I am using Axxess as my ISP, I have noticed that when i have connected my iphone to my WIFI it's unbelievably slow, in theory i am meant to have a 10Mbps line, I am using a DuoPlus 300wr modem would that have any direct impact at all

 

[Tacet]

What security settings are you using? What sometimes happens is that the encryption is done on software level rather than hardware, and that tends to slow a device down significantly. In such cases switching to something old like WEP can help, but at the cost of security. You can't win...

 

[Pictureperfect]

I am using WPA