Extremely slow WiFi on any OS

Hello.

I have an HP Envy 17 1150-ES on Windows 7. The network card is a Broadcom 43224AG 802.11a/b/g/draft-n Wi-Fi Adapter

There is no obvious problem while browsing internet. According to the connection status, it's connected at 130 or even 270 Mbps and the signal strength is OK.
Nevertheless, when I try to get files from my NAS, or stream, other laptops and phones in the same location get 5 MB/s or more, while this PC rarely gets over 300 kB/s.

I though it was a misconfiguration, but I booted up Knoppix and it was equally slow. This is what puzzles me the most.

I tried to replace it with one from another computer, but it gives and error message and refuses to boot, and the BIOS is locked (Insyde F.1D).

inSSIDer Home on this laptop detects every surrounding network perfectly on 2.5 Ghz and says my signal is the strongest around, at -51 dB on n (same as shows on other computers and telephones in the same spot).

I have changed the configuration on the router, from 11b,g,n to 11n only and the transmission for this laptop became even slower (74 kB/s).

• Is it possible for the card to fail this bizarre way, so that it detects and connects to networks, but becomes terribly slow? As I said earlier, it happens in both Windows and a Knoopix bootable USB, so it should'nt be a configuration issue.
• 
  
• Other than getting a USB wifi card: Is there any other option to try? I'd like to put another wifi card, but I'm afraid it will be rejected by the BIOS and I have no way of whitelisting it.

Thank you.

 

@alavena check if setting 2.4GHz channel width to 20Mhz in driver settings helps.

 

If I may ask a few questions:

1. What chipset is your wireless card?
2. Are you noticing abnormally high rates of packet drops?
3. Is there a difference between the speeds observed for UDP and TCP traffic?
4. Have you run an iperf test between your laptop and another computer on your LAN? If so, please post the results.