topic Re: APs Using Unassigned Channels in Wireless

APs Using Unassigned Channels

Jesutofunmi O — Wed, 08 Jul 2026 16:26:22 GMT

Hello,

I have set up a Cisco WLC 9800 with C9130AXI-E Access Points. I created an RF profile that only has the last 4 non-DFS channel (153-165). However, the AP never uses the assigned channels in the RRM-DCA config. It selects and uses random channels that are not defined in the RF policy/RF tag. I have checked and confirmed that the AP is indeed using the assigned RF tag which has the RF profile where I set my preferred channels. Does anyone, by any chance, know the cause of this?

The controller firmware is 17.15.5. See attached screenshots.

Re: APs Using Unassigned Channels

aleabrahao — Wed, 08 Jul 2026 16:37:39 GMT

In your screenshot, the channel width is set to "Best."
When DCA is permitted to choose the channel width dynamically, the AP can form 40/80 MHz channels from the channels you have authorized. The displayed operating channel may sometimes appear different from the individual 20 MHz channels you selected. Cisco's DCA algorithm takes into account both channel assignment and channel width.

I'd change the RF profile to a fixed 20 MHz width and see whether the AP remains on 149/153/157/161/165.

Re: APs Using Unassigned Channels

Mark Elsen — Wed, 08 Jul 2026 16:33:48 GMT

- @Jesutofunmi O Check if these channels are allowed in your country using https://apchannels.cisco.com/

Re: APs Using Unassigned Channels

balaji.bandi — Wed, 08 Jul 2026 16:40:10 GMT

May be worth trying fixed to 20 - best working for long working my profile

Re: APs Using Unassigned Channels

Jesutofunmi O — Thu, 09 Jul 2026 00:06:34 GMT

I had tried that before changing it to auto

Re: APs Using Unassigned Channels

Jesutofunmi O — Thu, 09 Jul 2026 00:10:15 GMT

I had manually set the channel width to 20MHz and assigned the last 4 channels but that didn't fix it

Re: APs Using Unassigned Channels

Leo Laohoo — Thu, 09 Jul 2026 00:18:23 GMT

Post the complete output to the following WLC commands:

sh ap dot11 5ghz channel sh ap dot11 5ghz summary

Re: APs Using Unassigned Channels

Jesutofunmi O — Thu, 09 Jul 2026 09:44:05 GMT

Hi Leo,

Please find attached.

JT

Re: APs Using Unassigned Channels

balaji.bandi — Thu, 09 Jul 2026 09:47:42 GMT

what was the outcome can you show us any output or logs to understand

show ap dot11 24ghz summary / show ap dot11 5ghz summary

Re: APs Using Unassigned Channels

Jesutofunmi O — Thu, 09 Jul 2026 09:53:44 GMT

Hi Balaji, pls find attached.

Re: APs Using Unassigned Channels

Leo Laohoo — Thu, 09 Jul 2026 10:09:33 GMT

@Jesutofunmi O wrote:
Channel Assignment Mode : OFF

Uhhhh wut?

OFF means "Turns off DCA and sets all AP radios to the first channel of the band, which is the default value. If you choose this option, you must manually assign channels on all radios."

Ideal setting is Automatic.

Reference: Configure 802.11 RRM parameters

Re: APs Using Unassigned Channels

Jesutofunmi O — Thu, 09 Jul 2026 10:09:54 GMT

Thanks Leo. I had spotted it too and changed it to Auto.

Re: APs Using Unassigned Channels

balaji.bandi — Thu, 09 Jul 2026 12:01:21 GMT

Looks like you're already in solution by configuring manually, which fixes the issue.

Re: APs Using Unassigned Channels

Jesutofunmi O — Mon, 13 Jul 2026 16:10:53 GMT

This was a very valid answer and perhaps the solution; only that I couldn't find my AP model on there - C9130AXI-E

Thanks to everyone who helped with this. The issue persisted after I changed the the Global RRM Channel Assignment Mode to Auto (and clearly, it should have been set to Auto, not off). However, the issue persisted because the APs were not using the global RRM. I had assigned a custom RF profile to the AP where I specified the channels I wanted (153-165).

I noticed that when manually assigning channels, the WLC did not allow the manual assignment of the last 4 channels (153-165), which were the channels I had attempted using in the DCA settings. The moment I switched to 4 other channels (44-56), the connected clients moved to it. It then made sense why the WLC assigned the first channel (36) to the AP at first.

In many European countries, the usable 5 GHz channels are primarily: 36–64 (UNII-1 / UNII-2A) and 100–140 (UNII-2C / DFS)

Channels 149–165 are generally not permitted in most ETSI countries, except the UK.

The AP I have is a -E domain AP, channels 153, 157, 161, and therefore has those channels disabled.

Many thanks again to everyone who helped with this.

Re: APs Using Unassigned Channels

Rich R — Tue, 28 Jul 2026 06:53:59 GMT

For future reference you can see the available channels at a glance with show wireless country channels: