Only getting 54mbps on Wireless-N

[phuz]

I recently noticed that my laptop was only connecting to my router at 54Mbps even though signal strength is excellent and I am in close proximity to the router.
I have two Cisco E1000 routers running DD-WRT and they are bridged in Mixed mode. When I look at the status of both routers' wireless speed, they are both floating around 150Mbps and most of the devices connected to them are at pretty high rates, too. It shows my laptop as 54Mbps for both TX/RX. Yes, my laptop supports N connectivity (Intel Centrino Advanced-N 6205) and it used to work fine. To verify the N functionality is still OK, I setup my phone as a hot spot and connected to it. Its connection rate was well above 54Mbps.

So why is the connection from my laptops wireless NIC, which is N, to my router, which is Mixed, running in G mode?

For another test, I put another laptop right next to this one and connected to the router at 144Mbps.

 

[phuz]

bump.

 

[bill001g]

I am going to guess the router is not running 40mhz channels. This is how it is suppose to run if it detects someone one a neighboring channel.

The 144mhz is very telling. The only way to get that is to run 802.11n on 20mhz channels with 2x2 mimo. If your other laptop does not support mimo it very well could only get 54m...even though 54m generally means it is running 802.11g.

If you have no old 802.11g stuff I would force the router to run 802.11n only with 40mhz channels. This should push your 144 laptop to 300m.

 

[phuz]

I'm not so much concerned with 144mbps. That could be because of distance from the router. But this particular laptop is clearly stuck in 802.11g (as stated in PROSet/Wireless) at 54mbps.

How do I tell if it does or does not support mimo? We are stepping out of the realm of what I understand. I am also confused as to why this used to work and for some reason has changed. My laptop and it's card have been the same.

I changed to N-only and 40mhz channel width and it has gone up, but I don't get why this was being limited it mixed mode. Now even though it's connected to the router at 144mbps now, the internet speeds have plummeted. 25Mbps downstream is now 0.5 - 0.6Mbps.

 

[bill001g]

In general it will have 2 antenna but unless you look at the wireless card its hard to say. I suppose you could look the part number up for the wireless.

That is the down side of 40mhz channels. You now have to find 2 clear channels you can use. 1,6 or 6,11. If you have a strong signal from a neighbor you now double your chance of interference. This is the huge mess of changing the options.

Mixed mode does tend to make things run slower because it sends data in a format the old equipment can tollerate. If you turn this off only 802.11n will run and it will free up this overhead.

 

[phuz]

I have no neighbors in range, so that isn't an issue. My card is definitely 802.11n capable. When I changed it to N - 40mhz width, the router said it was using channels 4 & 6. This is frustrating.

 

[phuz]

I have been watching my DDWRT status page on/off today and notice that the rate has been jumping around from 54mbps to 104mbps. Almost all devices are connected at over 54mbps but this laptop is still stuck. I just took another single band (2.4ghz / 300mbps) router that I have and set it up. I connected to it at 300mbps.

Before I pull my hair out, can anyone think of anything else that is limiting THIS laptop to THIS router? It seems all other devices are OK, but these two do not want to play nice together.

 

[Jeff_48]

I know this is an old post (not active since 2014) but today I run across similar problem and googled to this post. just want to share what I did hope will be add some value (not necessary or benefit to the original post by phuz though, since I assume he/she can not stay with the problem for years, must had solution already) but just in case there are other ones have similar issue may help them:

when I turn on the "WMM Capable" and turn off "APSD Capable" my laptop connected at 144Mbps
when I turn on the "WMM Capable" and turn on "APSD Capable" my laptop connected at 300Mbps
when I turn off the "WMM Capable" and turn off "APSD Capable" (while it is grey out) my laptop connected at 54Mbps

I might have different router or different software version, but this is just FYI.