Solved: wireless 802.11n connection limitation (fallback 802.11g)

[Mistermoonlight]

I am using merlin 378.50 firmware.

In all the devices i have on the wireless network, no device can connect to anything more than 54Mb/s, including my bravia tv (which is like 6 feet near the router but across a floor).

I am not able to configure in the gui niether any 2.4Ghz mode which supports 40MHz (the gui always returns to 20 MHz bandwidth mode).

After looking on wikipedia for 802.11n, it is suggested that "Assumes short guard interval (SGI) enabled" for more optimal bitrates. I did not find in the wireless pro section of the gui what option could be related to SGI?

I am also using b/g Protection option enabled.

Could it be something in my configuration that causes this?

If i am looking in wireless log, i can see the supported rates are:
RSSI: 0 dBm SNR: 0 dB noise: -87 dBm Channel: 11
BSSID: xx:xx:xx:xx:xx:xx Capability: ESS ShortPre ShortSlot
Supported Rates: [ 1(b) 2(b) 5.5(b) 6 9 11(b) 12 18 24 36 48 54 ]


Looks like it is configured to support 802.11 b/g only and not 802.11n which i could not see any supported rates (i am getting the same result if the wireless is configured for N only)?

 

[dorinspeedy]

Try wireless encryption WPA2 personal, AES, short GI. What router do you use? Put wireless channel a fixed one 1, 6 or 11, 40mhz channel width, how are much free in your surround if there is any other networks. Disable b/g protection.

 

[Mistermoonlight]

Try wireless encryption WPA2 personal, AES, short GI. What router do you use? Put wireless channel a fixed one 1, 6 or 11, 40mhz channel width, how are much free in your surround if there is any other networks. Disable b/g protection.

router asus rt-n66u with merlin firm 378.50.

Wireless is at fix channel 11
I could not set bandwith at 40 MHz (router refuses to do it)
Disabling b/g protection changes nothing at all (configure to N mode only changes nothing neither). According to the supported rates advertized, all devices could not connect any faster than 54 (they are all connecting at the max speed of 54MBps). I don't know where i can configure on the router short GI

 

[L&LD]

Are the bands set to Auto?

Have you reset to factory defaults and manually and minimally configure the router to connect to your ISP and secure the router?

 

[Mistermoonlight]

Are the bands set to Auto?

Have you reset to factory defaults and manually and minimally configure the router to connect to your ISP and secure the router?

Yes after updating, i reset to factory default and reconfigured everything

I have tried both, the 2.4ghz band set to "n-only" and auto, but this change nothing at all to the problem. Is the 5ghhz band related to this issue (the devices do not support both bands at the same time)?

I am already using aes wpa2 personnal.

 

[Mistermoonlight]

I am just curious can somebody get a wireless log and post it on the forum so i could see the possible rates when connecting at 802.11n?

 

[Mistermoonlight]

Ok, after factory resetting the router, i was able by setting to n mode and by enabling many of pro wireless option and using 40MHz bandwitdh, i could connect a tplink tl-wn722n at 150mbps as expected. So i have to figure out what configuration setting keeps my current configuration connecting at no more than 54mbps.

I have also figure out that in the wireless log, the max rate that can be seen in capability is always 54 Mbps, even if my tplink was able to connect at 150mbps!!! So there should be a bug there?

One thing i have noticed is that there is no HT capabilities advertized on the 2.4G band with the setup that refuses to go more than 54mbps (this setup does not want to use 40 mhz bandwidth neither)!

 

[KevTech]

2.4 GHz will fall back to 20MHz channel bandwidth when other networks are detected in your area and then connection speed will be around 65Mbps.

I use 5 GHz "N" only on my Panasonic TV and it connects at 300Mbps.

 

[Mistermoonlight]

Try wireless encryption WPA2 personal, AES, short GI. What router do you use? Put wireless channel a fixed one 1, 6 or 11, 40mhz channel width, how are much free in your surround if there is any other networks. Disable b/g protection.

You were almost on the problem dorinspeedy.

I have finally found the issue that was causing all n devices on the network to be limited to 54mbps (802.11g).

This seems to be a firmware bug and it is very weird:
If any of 2.4g 3 guess on the guess network is set to an encryption different than WPA2/AES even if this guess network is disabled, the basic 2.4 gHz network will fallback to legacy with 20 MHz bandwidth. What is really weird is that if you attempt to change the network bandwidth to 40 MHz in this situation, the gui won't let you do it without telling you why (you have an hidden disabled guess network that needs tkip/wpa encryption for example which is not compatible with 802.11n)!!!

Enabling the hidden faulty guess network and reverting its encryption to wpa2/aes and disabling the guess network solved the problem.

I was expecting that the router would ignore any guess network setting until it is enabled, but it is not the case

 

[Mistermoonlight]

You were almost on the problem dorinspeedy.

I have finally found the issue that was causing all n devices on the network to be limited to 54mbps (802.11g).

This seems to be a firmware bug and it is very weird:
If any of 2.4g 3 guess on the guess network is set to an encryption different than WPA2/AES even if this guess network is disabled, the basic 2.4 gHz network will fallback to legacy with 20 MHz bandwidth. What is really weird is that if you attempt to change the network bandwidth to 40 MHz in this situation, the gui won't let you do it without telling you why (you have an hidden disabled guess network that needs tkip/wpa encryption for example which is not compatible with 802.11n)!!!

Enabling the hidden faulty guess network and reverting its encryption to wpa2/aes and disabling the guess network solved the problem.

I was expecting that the router would ignore any guess network setting until it is enabled, but it is not the case

I'm just curious, does guess network stuff is always running under the hood, no matter if it is not enable on the interface, which would explain that buggy behaviour or it is just a firmware bug?