QUOTE(OKLY @ Oct 24 2014, 12:34 PM)
I'm using RT-N12 without the HP (high gain antenna) and yes WiFi performance is really not too good, end up I use another wireless access point.
High gain antennas help to improve the coverage, not optimum speed.
Previously when I was using TP-Link TL-WR841ND with twin 5dBi antennas (the same as your RT-N12), when I am more about 10m away (in my room) from the access point (at living room), the wireless signal became unstable and kept dropping & disconnected. However, the Asus RT-N12HP with 9dBi antennas solved this problem - stable signal & no disconnection.
As for the speed, it very much depends on the co-channels & overlapping access points in your area. If you stay at a landed house, chances are, the wireless co-channels & overlapping interference is not as serious as if you stay at a highrise condo.
You should have realized that there are 13 2.4GHz Wi-Fi channels available for you to set to. In the real sense, we all should be only using channels 1, 6 or 11 because the other channels will overlap with at two of these 3 channels. (See attached image)
So if you use Channel 11 while your immediate neighbor uses Channel 6, you are good to go (assuming no other neighbors)
However, if your immediate neighbor uses Channel 9, this creates an overlapping interference and caused the wireless signals to be distorted with errors, resulting in retransmission, thereby reducing the throughput (speed).
If your immediate neighbor also uses Channel 11 just like you, this is called co-channel, and the available bandwidth will be shared between you & your neighbor's access points. So you will notice that your throughput (speed) suffers if your neighbor is actively using to download large files such as P2P.
Problem is we all have more than one neighbor, and made worse in a highrise condo because you have neighbors who set to the same channel as you, overlapping channel as you, or even those who set to Auto that keeps changing the channels.
In such an environment, it is best to consider direct Ethernet cable connection to the router/switch instead of Wi-Fi. If pulling cables is not possible or you don't want to see cables laying around on the floor, nailed to wall or ceiling, spoiling the look in your house, then using HomePlug is a good alternative - this is what I am using to connect laptop & desktop PCs at home. I only use Wi-Fi for smartphones.
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