Failed to enable radio slot 2 because of 100 MHz spacing violation

[Mitch23]

Hi Guys,

I didn't find a solution for my bridge system's bug.

There is a small mesh system with 1 RAP and 4 MAP.

All of them are C9124AXE APs with 6 antennas.

The WLC is a C9800-40-K9, ver: 17.12.4

Almost everything is working except the slot 2 radio settings. It is working only with global settings, but the real problem is that it is using only 20 MHz.

So that's why I want to set all the slot 2 radio with manually.

But I always get the error message what you can see in my title.

I've found it in the bug search tool but it has no information about the solution.

The current config of APs:

Slot 0 -> 2,4GHz client access

Slot 1 -> manually configured backhaul on channel 100 with 40MHz width.

Slot 2 -> only works with global mode and i can't set it to anything

I hope someone could help me with this

Elsewhere i will open a TAC case.

Thank you in advance!

[Scott Fella]

Is your slot 2 the second 5GHz radio?  If so, you shouldn't use that. You should be concerned with the 2.4ghz, 5ghz primary radio and the 6ghz if that is what you want to tinker with.

[Mitch23]

Have you ever seen the data sheet of 9124AXE? Or are you just a bot? This AP has no 6GHz, and the client devices don't support it eitherway...
"ccess Points with three radios are designed for high density environments. The APs by default run one
dedicated 2.4-GHz 4x4 mode radio and one 5-GHz 8x8 mode radio. In the default mode, the radios are managed
by the Flexible Radio Assignment (FRA), and the Dual Radio Mode is in the disabled state indicating that
the radios have either been assigned as client serving 8x8 radio or have not yet been evaluated by FRA.
When you enable the dual radio mode setting, the 8x8 radio is split to two independent 5-GHz 4x4 radios. In
this mode, slot 1 and slot 2 are active independent 4x4 radio interfaces. They can serve different user groups
with different assigned channels."

-Misi
*** Can't rate the nothing***

[Dustin Anderson]

I don't have any dual radios to test with, but when I was trying to use the selectable on a 4800 as a second 5, I ran into the same error. They were AirOS so may not be the same, but I believe it was more referring to channel vs MHz. IE 36 and 136 etc.

Just to see if it's the same thing, can you set your backhaul to like 36 and see if you can set 140 on 2nd radio? If this is the case you can maybe work with it on a small deployment, but wouldn't scale very well.

[Mitch23]

I can't set the backhaul or any other channel below 100

I've checked in the Extended UNII B Domain Channels under Config / Wireless / Mesh / Global config / Backhaul menu, bot only channel 100-140 are allowed. My country code is Europe / Hungary. Channel 36-66 are allowed here.

[Dustin Anderson]

You could try it then with backhaul 140 and then a low channel. I would definitely open a TAC as it's not working as intended, but a workaround would at least get you working as any fix would be a code update that could take months.

Depending on bandwidth needed you may have to do 2.4 backhaul and just one 5 radio going. Not optimal, but sometimes you just gotta make it work for now.