Ubuntu – That pesky Intel Centrino wireless N + WiMAX 6150 wireless card

You need to disable the power management and possibly the 802.11n extension. These changes worked for me.

For the power management create a file in

sudo gedit /etc/pm/power.d/wireless

with the following content

#!/bin/sh 
/sbin/iwconfig wlan0 power off

and make it executable:

sudo chmod +x /etc/pm/power.d/wireless

To disable the 11n extension, try the following

sudo su
echo "options iwlwifi 11n_disable=1" >> /etc/modprobe.d/iwlwifi.conf

You need to reboot after those changes. Running iwconfig should show:

wlan0     IEEE 802.11abg

and

Power Management:off

What definitely worked for me was to upgrade to one of the latest kernel from

http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.17-rc4-utopic/

Further hardware testing

Your 1-day test in Win7 may be inconclusive. The Windows 7 driver may "drive" the wireless card differently than the Linux driver. If the Windows driver doesn't stress the wireless card in the same way, you may not see the wireless card drop off as quickly. If testing the card from Windows, I'd running it a couple days. A better test would be using an older version of Ubuntu that you have used in the past without trouble.

Don't trust the Dell diagnostic either. If their diagnostic passed, that just means that the card was functioning when they ran the diagnostic. If an electrical component on the card is malfunctioning, it may work fine after a reboot, like my friend's did, but only for a time. I had a friend that was experiencing similar issues on a Windows laptop (and using an Ubuntu LiveUSB on the same machine). My friend's card would pass diagnostic tests too because they could only be run after a reboot when the card was working. I replaced my friend's wireless card, and all of his problems went away.

From what I can tell online, it looks like your wireless card provides WiFi and Bluetooth. If the Bluetooth also stops working at the same time as the WiFi, it's more than likely that your wireless card is faulty.

Here are some things you can try for the purpose of troubleshooting:
Ignore the options you've already tried. I've only included them for the sake of anyone else who might stumble upon this post looking for answers.

• Download an old version of Ubuntu that you know the WiFi had no issues with (12.04?) and see if your WiFi drops while running the LiveOS. If it does, your wireless card is most likely faulty and needs to be replaced.
• Clone your existing system. Then blow everything away with a Windows install and see if you experience the same issues in Windows. If you do, it's time to replace the internal WiFi card. Restore the cloned image.
• If you have a spare hard drive lying around, pull the one in your computer, and install the spare. Then install Windows and see if issue persists. If it does, it's time to replace the internal WiFi card.
• Don't test anything. Just open your computer and yank the wireless card. Buy a replacement with the same model number. They're usually pretty cheap. I paid less than $10 (in China) for my friend's replacement. Drop it in. If the problem goes away, then the old card was obviously faulty. If it persists, then you're out the price of the card.
• Finally, whether the internal card is faulty or it's a hardware incompatibility problem, you should be able to buy a USB WiFi dongle and use that. Most are compatible with Linux these days. Unfortunately, most low-profile USB WiFi dongles have weaker reception than your internal card and won't come with Bluetooth which your internal card may or may not provide.