Kenneth Porter wrote:
Could you have a rogue server? Make sure it's getting the lease from the correct server. Try running Wireshark on the client.
The log on the server shows it received DHCPREQUEST for the old address without a preceding DHCPDISCOVER.
BUT... I have discovered that the Internet security device on the network is also running a DHCP server. My guess is that it is interfering with the process, possibly responding with an offer for the old address before the PC sends DHCPREQUEST. A classic race condition.
I don't manage that device so I'll have to request the necessary change. If things start working after that, I'll post a followup.
Thanks for all the advice.