802.11a/n/ac interface of AP is down (missing, lost, disappeared)

[Thomas M.]

Hi All

There are 5GHz interfaces disappearing from our installed AP's (mostly 2700 series). All together approx. 12 AP's in the last 3 months. PoE is not the issue. Country codes are all set correctly. We've tried on several of them to set them to autonomous and then back to lightweight. Also Power-cycle and Reset did not do the trick. It seems as the 5GHz physically is gone. Until now we just replaced the AP's but maybe someone has more input why this keeps happening as I'd like to understand if there was e.g. a bad batch of production or something like that.

Thanks! 

[Leo Laohoo]

Are the radios in error-disable?

[Thomas M.]

No, they disappeared completely. It is as the AP doesn't have any 802.11a interface at all.

(WLC) >show ap config 802.11a AP-NAME

AP does not have the 802.11a radio.

[Leo Laohoo]

What firmware is the controller running on?

[Thomas M.]

8.3.143.4

[Leo Laohoo]

That firmware is an engineering release. This behaviour could be a bug.
Try upgrading the firmware of the controller to something more recent.

[Thomas M.]

We had this issue on 8.0.152.0 as well as on 8.3.133.0, hence it's probably not a bug on the running code.

[Scott Fella]

Probably a bad batch if the radio goes missing. Open a TAC case to either get confirmation that it is a bad batch, a bug or something else. I have seen bugs creep up from older code versions, but Tac would be the only one to confirm if it’s the same or possibly a new bug.