I have been following this thread closely, as I suspected some issues a while back. The system I was using, had the antenna in the hinge area and was covered with some shiny metal, so I suspected that was some of my problem.
When I was doing this, I was in contact with someone from Intel(Sep 27, 2012), via email communications. I took the Intel® Centrino® Advanced-N 6235 adapter and was swapping it with the computers I had in my residence. I was in the same location for all tests. I did tests under load and emailed the results to the Intel Rep. I decided to reference the emails, which I leave on the server and information for the adapter/drivers was...
Adapter Information:
Name: Intel(R) Centrino(R) Advanced-N 6235
Driver Version: 15.3.0.16
I see these drivers are NOT available on Intel's website. If you have a Dell computer, the drivers are still available at...
Intel Centrino Advanced-N 6235 drivers
Download the drivers and save them to your desktop.
Make a system restore point.
(Windows 8) Hit the Windows key and the x keys at the same time
control panel, device manager, network adapter, right click on Intel(R) Centrino(R) Advanced-N 6235, left click uninstall. Tell it to remove the drivers and software.
Restart your computer.
When you log back in, the new hardware wizard will try to install the adapter but fail. Install the drivers you saved to your desktop.
What happens? I have seen issues with some virus programs and firewalls causing problems with the connections, but when that happens, you cannot get online at all(in most cases).
Rick