Comment 2 for bug 1569925

My first suspicion is that the interface that the iscsi device is on lives in /etc/network/interfaces (or interfaces.d/*) somewhere and thus is being shut down by networking.service. Ordinarily this network interface is being set up in initramfs by open-iscsi and should not otherwise be configured/touched by the OS (i. e. not by ifupdown, NetworkManager, or networkd).

 - Which network interface is the iscsi device on, and how did you configure this?
 - Please attach /etc/network/interfaces*

It would also be useful to attach a complete shutdown log. Do a reboot and attach /var/log/syslog, that should have sufficient data for the network interface shutdowns (it won't cover the open-iscsi error though as that happens too late, but we have that part in the screenshot).