Asus N56u with with Intel wifi 5100 problem

I just upgrade my Dell E6400 wifi card to Intel wifi 5100.
I connect white cable to 1 and black cable to 2 on the card.
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The Asus N56u is dual band router with maximum 300Mbps @802.11n.
The Intel wifi Link 5100 card is also dual band 802.11a/b/g/draft-N up to 300 Mbps of Receive Bandwidth.
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When I connect to 2.4G frequency, the maximum connection is 150Mbps, and will drop to 75Mbps sometimes when computer is idle
When I connect to 5G frequency, the maximum connection is 300Mbps, and will drop to 150Mpbs sometimes when computer is idle.
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My question is why I can not connect to 2.4G with 300Mbps ? I think both N56u and WiFi-5100 card support 300Mbps connection at 2.4G and 5G, but please correct me if I am wrong.

 

There are probably lots of networks on 2.4GHz band which causes the router to fall back from 40MHz channel with resulting in 300mbps connection to 20MHz channel (150mbps).
Noise and non-Wi-Fi devices on 2.4GHz band just add to the background noise.

You can use inSSIDer to scan the surroundings and see if you need to adjust the channel or not.

 

yea, there are 2 2.4G routers around my house, and my wireless homephone is also 2.4G frequency.
do you mean I need to adjust the channel in my router to avoid other 2.4G device? and the router is just 6 ft away from my laptop.

 

If it's possible you should choose a channel that is free and not overlapping with any other device shown by inSSIDer.
There are also other devices that use 2.4GHz band - Bluetooth, cordless phones, child monitors etc. There won't be visible on inSSIDer scan and you'll have to check all channels to find the best (if there is such a thing)

 

hmm, magic, it works.
I also change the channel width value to Auto instead of 20 MHz, right now I can see 300Mbps connection speed.
Thanks Downloads