I have one MR53 that is going offline intermittently. when i do shut/no shut on switch port it stays up for a bit and then goes offline. Could not find the root cause. Below are more details for you to help and understand the issue.
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Troubleshoot performed :
1. used another port on same blade - no luck.
2. used different blade - no luck.
3. replaced the cable - no luck.
4. connected different working AP on same port - works fine.
5. connected faulty AP to working AP port - no luck.
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Pic-1 - shows up for long period of time. In the morning suddenly it went offline.
Pic-2 - shows Event log of the AP.
Pic-3 - below is from Switch log. (interface Gi1/16 where the AP is connected.
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Mar 6 08:07:07: %ILPOWER-7-DETECT: Interface Gi1/16: Power Device detected: Cisco/IEEE PD
Mar 6 08:07:07: %C6K_POWER-SP-1-PD_HW_FAULTY: The device connected to port 1/16 has a hardware problem. Power is turned off on the port.
Mar 6 08:07:08: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/16, changed state to down
Mar 6 08:07:08: %LINK-3-UPDOWN: Interface GigabitEthernet1/16, changed state to down
Mar 6 08:07:08: %LINEPROTO-SP-5-UPDOWN: Line protocol on Interface GigabitEthernet1/16, changed state to down
Mar 6 08:07:08: %LINK-SP-3-UPDOWN: Interface GigabitEthernet1/16, changed state to down
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If it is really a hardware problem then why it would stay online from Mar 5 15:55 to Mar 6 08:09?
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Pic-1
Pic-2
It sounds like you covered all the basics in troubleshooting this. Do you have other MR53s and this is the only one misbehaving? You could try putting a known good one onto the connection your bad one is on, but since you're replaced all that run, and tried different ports I would expect it won't show much. For me, next step would be to RMA the bad AP.
Have you tried a factory reset on the device? If you've done that, and it's still exhibiting this behavior, I'm also Team RMA.
Sorry i missed that one. I did factory reset too with no luck.
Are you using or have you tried using a Power Injector?