@woozle Thank you so much!! You saved my life.. almost litterally, because my 10 year old twins are coming over, and hell would come down on me if they couldn´t play online :) 

  @madselhoff  Both new and old does not work. Can't find the T3U Plus 

  @NiHao21 

Can you please check the hardware ID of your T3U Plus? Previously the T3U Plus was reported to have VID_2357&PID_0138. (below a picture of another TP-Link adapter for reference)

If the drivers from TP-Link's product webpage for the T3U Plus somehow don't install, then you could try a driver provided by Microsoft.

https://www.catalog.update.microsoft.com/Search.aspx?q=VID_2357%26PID_0138

(note: the files with a size of 2.3 MB are for the 32-bit version of Windows, while the ones 2.6 MB in size are 64 bit)