On 07/12/2017 04:22 PM, mark wrote: > On 07/12/17 12:09, Gordon Messmer wrote: >> On 07/12/2017 07:13 AM, m.roth at 5-cent.us wrote: >>> 4. It appears to try, several times, and then give up - as our >>> manager puts it, "I to renew the lease", "Here it is","Nope, >>> don't like that, try again", and eventually, after 4 or 5 or >>> so tries, gives up. >> > Next, there is *nothing*, not in dmesg*, not in /var/log/messages, to > indicate when it failed, nor any failure message. No indication why > the daemon didn't restart it. Where did your manager observe the conversation you described above? If you're watching traffic at the DHCP server, have you tried also capturing traffic on one of the affected clients? Following the failure, does the client have an IPv4 address and no IPv6 address? Or does it have an IPv6 address and no default route?