Install the latest driver for Windows 8.1 and it should be solved then.
http://www.tp-link.com/en/download/Archer-T2U_V1.html#Driver

Hi Tony, thanks for the post!

I thought I already done this, because I installed it before my upgrade and after having upgraded to Windows 10, I couldn't update it anymore using device manager. Even when I pointed to the driver directory it said: "The best driver software for your device is already installed".
So I gave it another try, but using the tp-link utility setup and guess what happened... The driver installed perfectly :-)

Grtz!

Import piece of information for Windows 10 users outside of the US who have problems with the TP-Link Archer T4U Wifi adapter.
First change the display language of non-unicode programs in Windows. See this website for an instruction: http://www.tuicool.com/articles/YRJnUj.
Only then install the latest driver from the TP Link website. Don't let Windows search for the driver, select the location of the downloaded driver manually.