As in topic: adding a manual host (under Network/Edit Hosts) will stop Unbound but not start it again.
/etc/rc.d/init.d/unbound status
/usr/sbin/unbound is not running but /var/run/unbound.pid exists.
Possibly a crash. Starting it manually works.
I just tested that and did not find any problem with unbound stopping.
This was a fresh install of CU201.
The first line is testing the status on unbound and it is running with pid 1816.
The second line shows that the hosts file is empty.
The third line is showing the hosts file now contains a host.
The fourth line shows that unbound is still running and still has the same pid.
The entry I put into the Hosts file was the following entry in the WUI
So I have not been able to reproduce your effect.
I would look in the System Logs under the DNS: Unbound section and see if there are any messages about why unbound stopped running.
Yeah this was an out-of-memory error at restarting the process. Weirdly enough the RAM was at 90% – so not full – and a manual stop/start worked without any problems or error messages at all.