reuse_lease: lease age 1217 (secs) under 25% threshold, reply with unaltered, existing lease "

Those are common - leases normally don't start to renew until 50% done. But as the client gets closer and closer to lease expire, it should start screaming for a renew.. Sending them more and more often.

Once a renew fails - it should send a discover..

I would watch your logs the next time it happens and look right away, set your log to keep more in the gu.. I think it defaults to only the last 50 entries. I have mine set at 2000.. This should allow you to see more entries.

Good one , i just checked and don't see anything strange there , just once : "reuse_lease: lease age 1217 (secs) under 25% threshold, reply with unaltered, existing lease "