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C9120AXI stuck on 20 Mhz


Resulting in limited speed of 288 Mbps, rather than supposedly 866 Mbps on 80 Mhz (.11ac).

I have tried disabling DCA, setting custom channel to 80 Mhz, but my devices can only get 20 Mhz. Happens on various firmware from oldest to latest.

What's strange is on EWC dashboard it shows that my laptop is negotiated on 80 Mhz, but on the laptop itself it's still 20 Mhz (please refer to attachment).


Is this a bug or something i misconfigured?

4 Replies 4

VIP Collaborator VIP Collaborator
VIP Collaborator

Channel width negotitation is up to the client station while in the connection process. Additionally, that channel width is dynamically under permanent negotiation during the connection.

802.11ac standard has implemented a mechanism to avoid channel interference when multiple APs are using overlapped channels while using channel bonding. Before using such extended channel bondings, first thing you need to know is if there are other neighbour networks overlapping yours on the channels you are about to use, and if that networks's signal strength are above the threshold not to be able to use those channels.

Yo can find good explanation here.

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There's literally no other 5Ghz SSID in my neighbourhood. Another interesting find as the screen shot is the AP already broadcasting 80 Mhz but no client can't get traffic above 288 Mbps. Even my wifi 6 device is also stuck on 288 Mbps with this "enterprise" AP.


Try this -
1.does 40mhz work as expected.
2.on AP, manually set ch to 36, get client close to AP and test it. now capture rssi/rate/index.
3. if possible take over the air packet capture to see what's going on.

40 Mhz also stuck on 288 Mbps. I've tried setting it on channel 36, but my devices somehow can't detect the SSID on that channel. And there's no interference/obstruction issue.

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