I got it working! First and foremost, speed will always get down when you get away from the modem - we have to admit, that it does it more on these systems - compared to other laptops or other electronic devices.  So having that clear, I had updated the wifi driver to the latest one from 2014 and I was experiencing the mentioned issue, reading the things people have tried I decided to DOWNGRADE (ROLLBACK) the Wifi driver to an earlier version. I did this going to the adapter options, driver as the image shows.  HOPE IT WORKS FOR EVERYONE because this is a good machine and so sad that the design issue has affected all of us.[IMAGE]
I got my Brand new xps 15 yesterday, It works fine, looks great, I'm overall satisfied with it. (even though it gets warm all the time)   Problem is, the WIFI doesn't work well at all, I'm 2 meters from my box right now, And I'm not experiencing any problems, but as soon as I get upstairs in my bedroom, my signal speed drops significantly, I can't even load a youtube video, I was downloading a game from steam yesterday, and the dl speed dropped to 6mb/s!! That's awful, If this problem can't be fixed, I'll be returning mine, and won't buy any other Dell product, I don't see how a laptop that pricey can have that kind of problems. ( because I heard I wasn't the only one, a lot of people have the same problem)   Anyways, if any of you have a solution to fix my problem (Like a Bios), I'd be really grateful.   Thanks !   (sorry for my english, I'm french)
WIFI problems on Dell xps 15 L521X