Wi-Fi issue

[#1]

Wi-Fi connection and download speed using various tablets, laptop and one desktop using a TP link are fine with a download speed around 37, however one desktop using Linux (mint 17) is only showing a download speed of 2. The Wi-Fi signal is showing 57%
The desktop using the TP link is also running Linux mint 17 with no loss in speed, has anyone any ideas on what I can check out to resolve this problem.
There are a number of posts on the net from users of Windows but the answers are not relevant to me.

[#2]

Are they all on the same dongle? Check the channel in use is <10, had that issue with android devices. Also check that the dongle isn't faulty by switching them if they are the same.
It might also be local interference on the one pc.

[#3]

Thanks.
I Will have a go at trying another dongle, location of the dongle etc.
My tablet is running on Android and the speed is fine on that.