If you are experiencing this problem on your system, with a usb wi-fi adapter, then follow this tutorial to solve it.
The problem occurs because some of those cards does not have full compatibility with the network frequency of 5GHz. Because the device is configured to use by default the wireless mode 802.11b/g/n option, then the preferred connection will be the 5GHz.
To avoid your device to use the 5GHz frequency mode, you need to change the wireless mode to 802.11b/g option. With the 802.11b/g wireless mode your adapter will connect on your network using only the 2.4GHz frequency. It will solve the slow connection problem.
On windows search for Device Manager. After that, go to Network Adapters list and find your device. Now click on the “Properties” option. In “Advanced” tab change de “Wireless mode” to 802.11b/g.
