Wifi is not work properly while lid closed Inspiron 3521

Hello!

I'm using a Dell Inspiron 3521 and absolutely satisfied with it but I have a problem. I reinstalled the windows 7 a few days ago and the wifi is not work properly while the lid is closed. 

I looked up some forums and tried a few suggestions: 

Start-->Control Panel-->Hardware and Sound-->Device Managger-->Network adapters-->Dell Wireless 1703 802.11d/g/n (2.4GHz)-->Properties-->Power Management-->Allow the computer to turn off this device to save power (unchecked)

Power Options--> High Performance-->Change advanced power settings-->Wireless adapter settings-->Power Saving Mode-->both Maximum Performance

While the lid is closed the wifi conncetion is still alive but instead of 2 Mb/s it is 0.06 Mb/s (tested on speedtest.net) the ping is the same with opened and closed lid. I have reinstalled the driver but it is the same. Before I reinstalled the os there was no problem with wifi.

I have found a forum where they suggested somebody with the same problem to do this with the usb root hub:

Properties-->Power Management-->Allow the computer to turn off this device to save power (unchecked)

I have done this too but isn't helped.

Thank you for your aid!

Dávid Kovács