Turn off the battery saving feature when using WiFi.
Set the static IP address for the computer instead of the dynamically allocated address.
Reboot the WiFi modem (you unplug the power for about 5 to 10 minutes) then plug it back in for the modem to continue working.
Reinstall the driver for the wireless card compatible with Windows 8.1 operating system, so visit the hardware vendor's website and download the latest driver version for installation.
If the cause is due to the above errors, you can in turn do the following: