Cisco APs Randomly Reboots

[B A]

Hello.

This is what happens. Recently we replaced and connected 45 new AIR-AP1852I-E-K9 APs to non-PoE switches. However, we used TP-Link Power adapter to power all APs so WLC showed "PoE/Medium Power". To solve this we bought Cisco PWRINJ6 power injectors and replaced all TP-Links and as a result, WLC showed "Power Injector/Full Power". All radios were fully working and we were satisfied.

However, since that time three access points randomly reboot (3-5 times a day) and after a reboot they switch from "Full Power" to "Medium Power". There is no patter when they reboot. All 45 APs have the same firmware version.

What we did: we changed a power cable to an injector, we changed the injector twice, we changed a patch cord between the injector and a switch, we used a different port on a switch, we tested the cable between the AP and the injector... all is ok, we checked the configuration of these APs on WLC, we also changed the AP. But still no joy. No matter what we change, three APs reboot.

1. Why just three APs reboot? 2. Why do they switch to Medium Power?

Any Cisco expert here?

Thanks for any help.

[Deepak Kumar]

Hi,

As you are using the external power adaptor so it is not easy to say anything without APs logs. Can you check a few things:

1. Change the Power input source as If today APs are working on the UPS then switch to normal Power.

2. What is the APs firmware version? We noticed a bug to a similar issue. 

And, I am not sure, that it will help you or not but try as enable CDP on the APs and switch, Also set switch port as full-duplex

.

[B A]

We use recommended power injector for this 1852 model.

What kind of a log should I look for?

CDP and full-duplex are enabled.

Version:

[patoberli]

Ok, that software 8.5.140.0 is quite good. There is one update out, the 8.5.151.0, which fixes various bugs.
Release notes: https://www.cisco.com/c/en/us/td/docs/wireless/controller/release/notes/crn85mr5.html
I suggest you try that to see, if it fixes the bug.

You used 8-wire network cables, like Cat5e or higher?

[Leo Laohoo]

Go to Management > Tech Support > AP Crash Log
Are the APs there? Do the dates correspond to the dates you are talking about?

[B A]

There is no record in the AP Crash Log.

We use Cat5e and higher.

[B A]

Anybody else?

[patoberli]

Have you done the upgrade?

[B A]

Not yet. How do I upgrade just the specific AP?

[Leo Laohoo]

Remote into the AP and post the following output:
1. sh version; and
2. dir

[B A]

AP#sh ver
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Cisco AP Software, (ap1g4), C1852, RELEASE SOFTWARE
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2015 by Cisco Systems, Inc.
Compiled Sat Nov 24 22:01:12 PST 2018

ROM: Bootstrap program is U-Boot boot loader
BOOTLDR: U-Boot boot loader Version 30

AP uptime is 0 days, 2 hours, 58 minutes
Last reload time : Tue Oct 15 08:59:58 UTC 2019
Last reload reason : unknown

cisco AIR-AP1852E-E-K9 ARMv7 Processor rev 0 (v7l) with 997268/722644K bytes of memory.
Processor board ID KWC224903TL
AP Running Image : 8.5.140.0
Primary Boot Image : 8.5.140.0
Backup Boot Image : 8.3.143.0
2 Gigabit Ethernet interfaces
2 802.11 Radios
Radio FW version : f6d58b5e05c762162e07fe70e0671647
NSS FW version : NSS.AK.C.CS-3-fix2

Base ethernet MAC Address : 70:C9:C6:54:0C:30
Top Revision Number : A0
Product/Model Number : AIR-AP1852E-E-K9

"Dir" is not applicable for my AP.

[Leo Laohoo]

Can you try upgrading to 8.5.151.0?

[B A]

I do not plan to upgrade WLC or all APs. If there is a way to upgrade just one specific AP under the controller, please tell me how to do it. Thank you.

[Leo Laohoo]

Won't work. The controller manages the firmware of the AP. If the controller doesn't get the upgraded, neither will the AP.

[B A]

Since all APs have the same version and the issue occurs only on three of them, is it really necessary to upgrade?

With TP-Link or older Cisco power injector everything works fine except the fact that they provide only Medium Power. With PWRINJ6 three APs reboots.

This happens: After we manually disconnect PWRINJ6 from the AP and connect it back, AP boots and stays at Full Power until a random reboot (it occurs in 5-10hours). After the random reboot, it stays at Full Power just for 2-3 minutes, then switches to Medium Power. After each next random reboot is stays at Full Power for a while then switches to Medium Power back.

Background: We have 45 APs in a factory area. Cables are installed to the places that are not easy to access so there is no power outlet near by of any of our APs. Before the exchange, all APs were working fine... I mean there is probably no issue with a cabling or a power outlet or a new APs. Previous APs worked at that place.

If we use TP-Link power injector or any other, everything is ok, no reboots. (but we cannot use TP-Link because we get Full Power only with Cisco PWRINJ6 so we must use Cisco injector). With a PWRINJ6, three AP sometimes reboots. If it would be the AP firmware-injector issue why not all of them?

We have three places in the factory area and they are causing the problem. I do not talk about a specific AP, I talk about a specific places. No matter if we change the power outlet for the injector, no matter if we change the AP or cabling, three places are just problematic. Cables were tested and the result is that there should not be an issue. It happens in specific places so I would exclude it is an AP issue. I would exclude the infrastructure as well because the infrastructure works with other power injectors. 

We thought that the distance might be an issue but the distance between the power injector and the AP is in our case 70m, 40m and 20m. PWRINJ6 supports up to 100m. 

We intentionally use PWRINJ6 because it can provide 30W. The 1852 model requires about 21W.

I checked those logs. 
WLC -> Management -> Logs -> Message Logs
WLC -> Management -> Tech Support
AP ->  show ap client-trace events all
AP -> show logging

Are there any other logs I should look at?