Problem
After the upgrade to UCS 5 and a following restart from the system the ISC-DHCP does not start automatically anymore.
Solution
update-rc.d -f isc-dhcp-server remove
systemctl disable isc-dhcp-server
systemctl enable isc-dhcp-server
update-rc.d -f isc-dhcp-server defaults
Investigation
Search for “K” and “S” runlevel files in /etc for isc-dhcp
find /etc -name \*isc-dhcp-server\*
/etc/init.d/isc-dhcp-server
/etc/rc1.d/K01isc-dhcp-server
/etc/logcheck/ignore.d.server/isc-dhcp-server
/etc/default/isc-dhcp-server
There are not all runlevels filled up with the isc-dhcp-server for starting or killing the process.
After the solution was done it should show up
find /etc -name \*isc-dhcp-server\*
/etc/rc6.d/K01isc-dhcp-server
/etc/rc4.d/S04isc-dhcp-server
/etc/rc5.d/S04isc-dhcp-server
/etc/init.d/isc-dhcp-server
/etc/rc0.d/K01isc-dhcp-server
/etc/rc1.d/K01isc-dhcp-server
/etc/rc2.d/S04isc-dhcp-server
/etc/rc3.d/S04isc-dhcp-server
/etc/logcheck/ignore.d.server/isc-dhcp-server
/etc/default/isc-dhcp-server
Root Cause
Investigation happens under the following bug report:
https://forge.univention.org/bugzilla/show_bug.cgi?id=55466
Additional information
Related problem is reported and fixed in this thread as well: Since UCS5 dhcp- server does not start automatically