This log did not help me either because during this specific time there was no logs in the engine.

2016-10-12 09:51:35,296 INFO  [org.ovirt.engine.core.bll.storage.domain.IsoDomainListSyncronizer] (org.ovirt.thread.pool-8-thread-13) [141b5168] Finished automatic refresh process for 'ISO' file type with success, for storage domain id 'fd5754f1-bd00-4337-ad64-1abde35438ae'.
2016-10-12 10:42:49,188 INFO  [org.ovirt.engine.core.bll.EngineBackupAwarenessManager] (DefaultQuartzScheduler8) [63f92190] Backup check started.

This means that it is not the engine attempting to connect.

@Simone can you please check whether this is hosted engine?

Looking more in to the logs I see that after hostdeploy there are no more attempts to connect from the engine:

2016-10-03 23:28:47,891 INFO  [org.ovirt.engine.core.uutils.ssh.SSHDialog] (DefaultQuartzScheduler8) [4afdc494] SSH execute 'root@ractor.mynewdomain' 'umask 0077; MYTMP="$(TMPDIR="${OVIRT_TMPDIR}" mktemp -d -t ovirt-XXXXXXXXXX)"; trap "chmod -R u+rwX \"${MYTMP}\" > /dev/null 2>&1; rm -fr \"${MYTMP}\" > /dev/null 2>&1" 0; tar --warning=no-timestamp -C "${MYTMP}" -x &&  "${MYTMP}"/ovirt-host-mgmt DIALOG/dialect=str:machine DIALOG/customization=bool:True'

Later in the logs I can see bunch of redeploys but no sign of attempt to connect.

Can you please share one of the host deploy logs?

According to the logs this is the last one: /var/log/ovirt-engine/host-deploy/ovirt-host-mgmt-20161011233340-ractor.mynewdomain-23718eb3.log

Thanks,

Piotr