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Data rate does not exceed 400 mbit/s


I am (re)opening a discussion because I have a problem with wireless data rate (does not exceed 400mbps).

I have 7 Cisco 9115AXI APs geographically separated, using EWC Catalyst 9800.

I read this post, but my problem is not resolved : 

I am using WiFi 6 on my computer, my driver is up to date on my computer.

There is details of speed connection :

EWC#show wireless client mac-address XXXX.XXXX.XXXX detail | in Rate|Signal
Current Rate : m11 ss2
Supported Rates : 6.0,48.0,54.0
  Radio Signal Strength Indicator : -50 dBm
  Signal to Noise Ratio : 41 dB

Sometimes the current rate is m9 ss2 or m10 ss2 (Why ? There is modulation switching (I am refering to mcs index table)?)

I want to configure 80Mhz channel-width (I have low user density but I want high speed connection to my LAN, I don't have neighbor wireless network on 2.4ghz and 5ghz bands). There is the 5Ghz RF profile configuration :

ap dot11 5ghz rf-profile high_speed
 channel chan-width 80
 no channel foreign
 rate RATE_12M disable
 rate RATE_18M disable
 rate RATE_24M disable
 rate RATE_36M mandatory
 rate RATE_6M disable
 rate RATE_9M disable
 no shutdown

I have an another strange issue but I think it is not linked to the main problem : two neighbors AP are using same 5ghz channels, but other are using good channels)

Thank you for your help in advance.

Jesus Pavon

Hi Torken,

MCS index depend on the SNR that is computed based on received signal strength (RSSI) and background noise. If any of these values changes, and they do as signal strength could change even without moving due to the very nature of the RF, then MCS Index change. In particular, MCS Indexes 10 and 11 are very difficult to maintain as they require crystal clear RF environments.

But if you are moving from the AP, then MCS Index would shift down.

With that been said, what you are noticing with MCS index shifting is normal so don't worry.

With regards on the RF profile you have, this is good for 80 MHz width. But what I would recommend you is to use almost one mandatory data rate that is recognized in the IEEE 802.11-2016 standard as been mandatory for OFDM transmissions (6-,12-,24-Mbps) as there could be some problems with certain devices if you mandate a non-standard basic data rate.

Lastly, regarding the 2 overlapped APs, channel overlap is normal if channel mapping is managed by RRM algorithm and the number of available channels is less than the number of APs, or there is a channel interferer. If you have more APs than available channels in your deployment this is unlikely your APs are going to use @80MHz channels so they will reduce channel bonding dynamically. You can only use 6 non-overlapped 80Mhz channels using full UNII-1-2-3 bands (5 of them if you remove TWDM channels; 4 of them if you are not allowed to use UNII-3 band like in ETSI domain).

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Hello Jesus,

Thanks for your interesting answer.

At this time, I am trying to get a better data rate (1Gbps, this is my dream, or at least 2 x 400mbps), that is why I disabled data rate under 36M (Testing stage).

I have the same data rate with 40 or 80 Mhz channels width this is not normal and I want to know why ?

I don't have any more overlapping after 3 RRM algorithm execution 

Thanks in advance

Jesus Pavon


If you are having the same data rate in both 40- and 80-MHz is because the AP may be detecting co-channel interference on any of the bonded channels and it's adapting to it.

You can also check you have latest drivers in you wNIC and you-re running latest recommended software on the controller/APs.

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How can I resolve co-channel interference ? I noticed that some printers are broadcasting autonomous wireless network, I will disable it and see if data rate will increase.

My wNIC is up to date : Intel(R) Wi-Fi 6 AX201 160MHz -> Driver version :

EWC software version :

EWC#sh ver
Cisco IOS XE Software, Version 16.12.04a
Cisco IOS Software [Gibraltar], C9800-AP Software (C9800-AP-K9_IOSXE-UNIVERSALK9-M), Version 16.12.4a, RELEASE SOFTWARE (fc1)
Technical Support:
Copyright (c) 1986-2020 by Cisco Systems, Inc.
Compiled Fri 31-Jul-20 21:50 by mcpre

AP software version :

AP Running Image     :
Primary Boot Image   :

It should be ok when I look at this web page :

I shutted down all printers and the data rate still low....  I realy don't know what to do ...

I am using WinFi software to scan wireless information :


I have 3 differents network (the first is hidden), and I can receive 3 different AP as you can see on the picture

Maybe it can give you information that I miss

Could you open a cmd and enter the command 

netsh wlan show interfaces

And please post the result here?


C:\Users\j>netsh wlan show interfaces

Il existe 1 interface sur le système :

    Nom                   : Wi-Fi
    Description            : Intel(R) Wi-Fi 6 AX201 160MHz
    GUID                   : 00000000-0000-0000-0000-000000000000
    Adresse physique       : d8:f8:83:00:00:00
    État                  : connecté
    SSID                   : AAAAA
    BSSID                  : ac:4a:56:00:00:00
    Type de réseau           : Infrastructure
    Type de radio             : 802.11ax
    Authentification         : WPA2 - Personnel
    Chiffrement                 : CCMP
    Mode de connexion        : Profil
    Canal                : 36
    Réception (Mbits/s)    : 1201
    Transmission (Mbits/s)   : 29
    Signal                 : 99%
    Profil                : AAAAA

    État du réseau hébergé : Non disponible

sorry my windows is not in english


No problem. Is this an original built in card or an after-market ebay/Ali one?

I ask because the GUID is empty, this is sometimes with broken installations or broken/counterfeited cards. You could try to uninstall the adapter completely in Device Manager, reboot, and install it again. Don't forget to first download the driver if you do this


What you can see here are the following two important informations:

    Réception (Mbits/s)    : 1201
    Transmission (Mbits/s)   : 29

So the card is actually connected with 1201 Mbps. The low Transmission rate could be, because of power saving features of the Wi-Fi adapter. That number should rise if you send large data to the network (for example running iperf,, ...). 

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