R81.10 Take 130
Since the environment was upgraded from 5000 to 6000 appliances recently, we faced twice the issue that all DHCP services stopped working suddenly with the symptoms seen in sk158974 which is an old SK not relevant anymore if we trust the affected versions.
The appliances are configured with a mix of DHCP relay and server along with the new services as it has been for years.
Additionally, /var/log/messages shows that DHCP requests arrived on interface X and dhcpd.conf should be edited to allow DHCP on that interface.
The workaround is to failover which immediately solves the issue, reboot the appliance and go from there.
We will open an SR, maybe this issue has been seen by some CheckMates.