DHCP issues in Wireless network with version MR29.4.1 and MR29.5.1

[eastoscar]

Hello community,

I have many of these log entries in my connection logs:

   Client made a request to the DHCP server, but the DHCP server rejected the client's request.

   Client made a request to the DHCP server, but it did not respond

I was already able to rule out the DHCP server because I initially used the Windows DHCP and later the DHCP server of a Meraki MX. I have this issues on the following MR Versions:
MR29.4.1

MR29.5.1

I recognized this logs only with Windows clients, but I don't have many others in my network so I can not really enclose...

Does anyone else have these problems?

regards Daniel

[Erminux]

Yes, I'm having the exact same issues. I'm just physically plugging everyone in as don't have the time to investigate but it is really annoying. 

[cmr]

How are your wireless networks configured, we don't have that issue on 29.5 and 29.5.1

[RaphaelL]

 Client made a request to the DHCP server, but the DHCP server rejected the client's request   Means that the DHCP server responded with a DHCP NACK.  Take a packet capture and look for DHCP NACKS. Most of the time they are caused because the client is requesting an IP that is not valid on that subnet ( eg : client is comming from floor X or building Y with IP 2.2.2.2 , but vlan that the client is connected is in the range 3.3.3.0/24 )

[WB]

Have the correct VLAN setup on your SSIDs? We have over 30 individual networks running on 29.4.1 with no DHCP issues..

[eastoscar]

yes, I checked it...

[eastoscar]

Hi,
I know that clients will do a DHCP request when they roam and that it is possible to that a different IP is in the request... but in my environment this should not be the case. The main problem I have is that sometimes clients request IPs and they immediately lose it and take another one. This happens 3-4 times till the client claimes his IP...  The old IP Address are marked as Bad Address in the DHCP Server scope. The only log I see in the same time as this happens to random clients in my wifi are the above 2 log messages.

[eastoscar]

Hey, problem was that the Client Balancing behavior changed with MR29.1 Version.

https://documentation.meraki.com/MR/Other_Topics/Client_Balancing#Client_Balancing_Behavior_-_MR_29....

For some reason the client flapped between two AccessPoints and because of that the client did send a lot of DHCP Requests, Discovers and DHCP Decline messages... I turned off Client Balancing and it seems to be OK.