Alienware X51 wifi problem

Hi, I just got an alienware x51 r2 with i7 4770/8gb/1tb/r9 270/DW1550/Win8 like a week ago and everything was working fine until I upgraded to 8.1

First I could connect to the wifi network but getting low internet speed or sometimes none while my other wifi devices were working fine, so I decided to go back to windows 8 using alienware respawn

When I tried to connect the new windows 8 installation my wifi network was not visible and again my laptop and others were seeing it

I have to say that I live in mexico and my wireless router is a Technicolor tg582n so no support for me

For what I have read here I think the solution will be buying a new adapter but first I wanted to ask you guys if there is something I can try to be 100% sure that my current adapter is damaged and if so, whats the best replacing option?

Alfredo