Hi diogodavid,I recommend uninstall/reinstall the updated wireless drivers on the computer: I have provided a link for drivers download:[URL] Download:  Install: If the issue persists, check the wireless connection in Safe mode with networking (restart the computer and tapping F8 on dell logo. Select Safemode with networking).If the wireless connections are still slow in Safe mode with networking, try updating the update the wireless router's firmware to the latest available. For more information, I have provided a link below which can fix the issue:[URL] check below mentioned links which would also help you with the settings for wireless internet:  Please let me know if you have any other queries.
I purchased a Ultrabook XPS L321X and the wireless connection is slower than I normally have. The adapter properties Description is "Intel(R) Centrino(R) Advanced-N 6230" I also have a old Laptop XPS MI1530. I made a test where I downloaded the Microsoft Office from the official site, from the Ultrabook XPS L321X it was downloaded with a rate speed of 60 KB/s and from my older laptop XPS MI1530 the speed was 1000 KB/s.  I have just purchased the Ultrabook XPS L321X and it is manufacture setting, however the internet speed is very slow. I tried everything, but I did not find a possible issue why the speed is slower than my older computer. Could you help me to fix that problem? I tried to contact dell but with no response.... Thanks...
Ultrabook XPS L321X - slow internet connection speed