40 Mhz plocio daznis 2,4G dazniu juostoje apskritai yra problematiskas, 
isskyrus atvejus, kai aplink nera kaimynu (su wifi)

http://www.smallnetbuilder.com/wireless/wireless-features/31743-bye-bye-40-mhz-mode-in-24-ghz-part-1


"Bronco" <TRINTI_bronco.mail@gmail.com> wrote in message 
news:l5qq59$d5j$1@trimpas.omnitel.net...
On 2013-11-11 10:29, rycius wrote:
> Gal galetum pakomentuoti kodel ?

Wifi N standartui tai priklauso pagal spec'us. Jei neijungsi WMM, gali
net gauti suletejima iki 54 Mbps. Nors ne visi routeriai taip daro, bet
buna ir taip. Jei nepatinka, QoS kompe gali isjungt, bet routeryje WMM
palik. Arba, pasibandyk praktiskai. Kai kurie routeriai, isjungus WMM,
wireless N rezime greicio nenumeta, netgi priesingai, rodo maksimalu
pralaiduma testuose 10-20 proc. didesni, bet tai testai, realiai
naudojant visokius p2p, voip ir video stream vienu metu, WMM gali labai
pasiteisinti.

http://www.smallnetbuilder.com/wireless/wireless-features/30938-dont-mess-with-wmm

Basically, the 802.11n spec requires devices to support 802.11e (Quality
of Service [QoS] enhancements for wireless LAN) in order to use HT (High
Throughput) link rates, i.e. higher than 54 Mbps. (WMM is a subset of
802.11e that was created by the Wi-Fi Alliance as a stop-gap measure
while 802.11e made its way slowly through the IEEE review process.)
WMM's Traffic Identifier (TID) field is key to aggregation mechanisms,
including block acknowledgement (block ACK), that enable 802.11n's high
throughput rates.

Since WMM support is required for products to be certified for 802.11n,
WMM comes enabled by default in all Wi-Fi Certified n APs and wireless
routers. So even if you don't have any WMM-aware devices on your
network, leave WMM enabled or you may find your clients connecting only
at 54 Mbps rates.