WMM mode is enabled on the routers as well...
I understand your router uses WPA2/AES. You may want to verify that the profile used in your computer by Windows* or by Intel® Proset Wireless Software is correctly configured since using a different security setting such as WPA2/TKIP or WPA2/[TKIP+AES] may cause this issue.
In case the issue persists it might be better to try with the connection as unsecured and that way you will see if it that makes a difference.
I have checked options in both Windows settings and in the Intel Pro software, but they are set to WPA2 / AES.
I have also disabled security on the router, but still gets 54Mbit connection.
But I`m a bit unsure with the network card settings in the device manager. In wireless mode it shows 6 options. But non of them are a N network.
And when I check for wireless networks that is available with the Intel Pro software it recognize the N network as an A network.
It cant see any N networks at all. Only G and A.
The Wireless Mode drop down menu has six options which include 802.11a/b/g. There is another property named 802.11n Mode which can be Enabled or Disabled. Is it possible that you modified your system with the Intel® Proset's Administrator Tool?
The property 802.11n Mode is Enabled.
No, I havent modified the system with the Intel Proset Admin tool.
And I have checked all the settings in the Advanced settings for the network adapter.
Is there any possibility to fix this with the Intel Proset Admin Tool?
You may create a new package, save and execute it to try to overwrite the settings in your system.