what would make an 802.11n card stop working 'n' speeds?

[Toadster]

Yesterday I cleaned out my media center PC and it has a wifi card onboard - Intel Centrino 6300 AGN card and previously it used to connect at 300Mpbs - to my Dark Knight WiFi AP

but now if it connects to the router, it's like 13Mbps (or 6) and the link retries all the time - keeps failing - essentially no connection...

if I set the adapter to 802.11g mode it will connect to the 2.4Ghz "G" antenna and run all day long at 54Mbps

it had been running at 802.11n speeds for months but now it won't sync...

My Asus RT-N66U WiFi Router is pretty stout, has 3 antennas and can run separate 2.4Ghz and 5Ghz bands...

I previously had this system setup to use the 5GHz antenna (one of a few devices that can run 802.11n in my home) - and the other devices in the home connect on the 2.4GHz 802.11g antenna

now when I try to connect to the 5Ghz antenna it syncs at 6 or 13mbps instead of 300-450 and essentially the link is ununsable to surf or do anything, but connecting at 802.11g it's rock solid >94% signal


what could have changed???

 

[Toadster]

Nobody?

 

[drebo]

Any G device connecting to an N access point will drop the speed of the entire access point to G speeds.

Thus, it's typical to run G devices on 2.4ghz and N-only devices on 5ghz.

The reason your 5ghz connection is so much worse is because the wavelength of 5ghz signal is much smaller than 2.4ghz signal, and thus it loses much more strength as it passes through objects.

 

[alkemyst]

It can always be a hardware/physical failure too.

 

[Toadster]

Any G device connecting to an N access point will drop the speed of the entire access point to G speeds.

Thus, it's typical to run G devices on 2.4ghz and N-only devices on 5ghz.

The reason your 5ghz connection is so much worse is because the wavelength of 5ghz signal is much smaller than 2.4ghz signal, and thus it loses much more strength as it passes through objects.

this is how I have it setup, one antenna on 2.4GHz with 802.11g
the other antenna @ 5Ghz with 802.11n

its' worked flawlessly for months, and now it stopped connecting on the 'n' antenna