Atheros AR5B97 - No internet connection over wifi

[ISwearSheSaidSheWas18]

Hey mates,

presently I have some issues with my internet connection over wifi. Previous, I used BackTrack and the wifi worked there very well, so instead of reinstalling BackTrack,
I'm more interested to know where the problem is and want to fix it with your assistance. My internet does work over ethernet cable, when I plug it out my internet connection slows extremly. It takes over 15 seconds to connect to google.
Its quite "working" but definetly not 6.5 Mb/s which represents my internet connection on ethernet. After hours of thinking, researching and filtering forums and sites, I decided to take the risk and posting my problem online. Hopefully, I dont overlook here something.

I used the Wireless Troubleshooting Script from Wild Man, Krytari, which creates a detailed information about my wireless. To see a detailed information, see attachment wireless-info.txt

[undersc0re]

Is that a hard disk installation? What have you tried to get it to work so far?

[ISwearSheSaidSheWas18]

Exactly, it's a hard disk installation, which worked fine with BackTrack for 1 year ago.
My first thought was, there would be a problem with my DHCP configuration, so first I checked my settings and seems like my notebook(kali) has the permission to access.
I have a internet connection over wireless but its reduced extremly. Usually 6.5 MB/s but in this case its less than 16 kB/s which takes me about 15~20 seconds to connect to google.
Tried to edit the ath9k configuration with:

 echo "options ath9k nohwcrypt=1" > /etc/modprobe.d/ath9k.conf

also tried to turn off the automatic power managment of ath9k with:

 iwconfig wlan0 power off