Powerline extender will broadcast Wi-Fi signal if Wi-Fi function is enabled. But to access internet, you have to ensure that it is paired with the one connected to the main router and they can...

Disable power-saving. http://forum.tp-link.com/showthread.php?3666-how-to-solve-some-powerline-adapters-can%92t-be-waked-up-by-some-network-adapters

What kinds of VPN connection? Can you provide the current topology?

@TimW Hardware and firmware version of your W8968? Did you try to disable UPnP?

I'm afraid not. The driver has to be installed on the right PC before we connect Wi-Fi.

Download the driver first. http://www.tp-link.com/en/download/Archer-T2UH_V1.html#Driver Follow FAQ228 to install the correct driver. If you still cannot install it, provide screenshot of the error.