Ap Attempted to use IP Address assigned to another device code 3

[robert P0]

Hello, I'm trying to configure a wlc and an ap.
I configured the wlc but when I try to connect it to the wlc it tells me :
Client Excluded: MACAddress:f4:4e:05:80:60:4c Base Radio MAC :f4:4e:05:80:60:4c Slot: 0 User Name: unknown Ip Address: 192.168.100.213 Reason:Attempted to use IP Address assigned to another device. ReasonCode: 3

But this ip is not taken by any device

AP:air-cap2702I-E-K9

WLC:2500 series 

both have factory reset 

[Scott Fella]

Check your dhcp server and also make sure that if you are using static address, that you reserve those addresses so that they don't get handed out by dhcp.

[robert P0]

I checked, no device has that IP, I made it static and it has the same problem

[Scott Fella]

So if you powered down that device show above with the mac address, can you ping that ip get a response?  Is there any arp info on the router for that ip address?  That ip isn't used on any network device? Also, is it just that one ip? If so, just reserve that for now until you figure out what else is using that.

[Rich R]

1. Make sure you're using the latest version of code: 8.5.182.12 (link below)

2.  > I made it static and it has the same problem
That can actually cause a problem if you have DHCP Required configured on the WLAN

3. Run a packet capture to see whether anything else is responding to ARP for that IP.  For example if you have proxy arp enabled on a router interface it might be responding and causing the problem.  As a general rule you should keep proxy ARP disabled everywhere unless specifically needed for something.