ER6120 V3 DHCP issue

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ER6120 V3 DHCP issue

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ER6120 V3 DHCP issue
ER6120 V3 DHCP issue
2020-05-20 16:43:25 - last edited 2021-04-19 11:04:54
Model: TL-ER6120  
Hardware Version: V3
Firmware Version: 3.0.1 Build 20180724 Rel.80086

I have a verry anoying issue in my lan and i think its related to the DHCP server from ER6120

 

below is the network topology

 

Internet ---ER6120---Cisco SG220- 3xEAP245

 

All 3 EAP 245 are on omada software controller and provides wireless access. The issue is that some wireless clients gets rejected when trying to get an IP and i see in the log files of the ER6120 the following 

 

DHCP Server rejected the request of the client[MAC: 08:c5:e1:39:30:28 IP: 172.32.0.70]

DHCP Server rejected the request of the client[MAC: 98:da:c4:fc:d3:de IP: 172.32.0.67]

 

and of course internet or lan access on this clients does not work. Setting a static IP on clients works. Sometimes i see in the DHCP Server reject message the MAC of one of the EAP245 access points - this is really strange since all 3 EAP245 are on static IP.

 

Also, no fancy configurations, everything is on default, no VLAN or VPNs

 

Any idea ?

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Re:ER6120 V3 DHCP issue
2020-06-12 05:52:56 - last edited 2021-04-19 11:04:54

@Rtdz 

 

You can access the menu Firewall -> Anti ARP spoofing -> IP-MAC binding , check if you have IP-MAC binding list.

Or when your client cannot get IP address, try to check the DHCP client list on ER6120. For confirming whther the IP address already been used.

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Re:ER6120 V3 DHCP issue
2020-06-12 08:12:43 - last edited 2021-04-19 11:04:54

@Andone 

 

Issue was solved! It was a rougue dhcp server on the network! Thats why the er6120 showed that errors in the log!

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