Why Is The Internet Connection Slow On My Windows 8 Pc

2 with windows 7 and one with windows 8. In addition 2 android smartphones.

ALL are connected to a wireless network connection.

When checking the internet speed on all three of the PC machines i always get a low result on the Windows 8 PC.

I tried to replace the wireless USB dongle, but still results are poor.

How can I monitor the reason for the poor result?

Is it the hardware? Maybe the software? Something else?