DHCP lease on management will not renew

Our managment IP on our radios is set via DHCP (1 day lease). We recently installed a new router at a tower and that changed the management subnet / DHCP server. I expected the radios to grab a new IP within 24 hours. It's been 3 days and none of the radios (except those that customers rebooted) have grabbed new IPs. The old subnet is no longer accessible so we can't access those radios to force a reboot. If I log into the AP and de-register them from the AP, they will pop off, come back and still have the same old IP.  Shouldn't a 24 hour lease tell the client (SM) to re-acquire after 24 hours??? It does not seem that the ePMP SMs do that...


I tried to reproduce the problem and I can't confirm that we have such a defect. 

I configured DHCP server with lease timeout 300 sec (5minutes).

Rebooted the SM and switched off DHCP server after SM got its IP.

Tcpdump shows that SM sent two unicast DHCP requests to renew IP after 150 and 300 seconds as expected.

The server was unreachable so it stopped using the IP after 5 minutes and started to send broadcast "DHCP discover" messages to find another DHCP server. In the end, I turned on DHCP server back and SM got a new IP.

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