I am in process of moving some functions from my old and trusted Synology box on the freenas. I want to also automatise most of things in case I need to recreate them again.

The first step in my process is to create jails, with DHCP. Process is straight-forward via the UI:

jail

I hit a snag when I tried to start it:

error

Sooo... we can't obtain a DHCP address. That's not nice.

I found here that I needed to enable promiscuous mode on the ESXi box. I logged in on the box and went to the Networking section and selected my vSwitch0:

vswitch

Then, I selected the Edit settings button (top-left-ish of the switch pane) and got:

settings

I opened the Security section and enabled promiscuous mode. The change is instant.

After this, I started the jail again. Success! :)

HTH,