Problem
You see a messages like this in your logfiles:
DHCPDECLINE of 172.26.6.185 from 00:16:41:bc:75:b1 via 172.28.11.253: not found
Solution
This could be a deeper problem, and more details should be provided, but it happens again and again that a DHCPDECLINE from the client comes when the client does not understand or cannot make sense of the information provided by the DHCP server.
So the client checks among other things if it finds e.g. the IP address over arp- then another client has it already and it rejects the IP with DHCPDECLINE and hopes for a new IP. But because obviously the MAC address is fixed in the UMC of this IP, the DHCP server can only deliver this.
Depending on the netmask, the client may also be on the wrong network and therefore refuse to accept the IP. Please review your network infrastructure, Hardware and Software correctly and in detail.
Helpfull tools:
- ping
- arp
- univention-ldapsearch
- nslookup “you client IP or name”
- traceroute
- univention-s4search
- ip -c