Interesting indeed. I have noticed the same (or similar, still trying to get a good picture of the situation). I noticed that several menu items in the web interface did not respond at some point (more details below). When I look at the ip addresses I notice that directly after boot I have my FreeNAS ip address listed as Primary NIC in the dashboard, but after a while (when jails have started) I see another address, one of my jails. What is more worrying is that on the console I see three ip addresses listed as web interface addresses. .16 is the primary address and .81 and .86 are jail addresses (fixed). The web interface is indeed available on all three addresses. Reboot doesn't solve the issue.
I arrived at this situation after doing a clean install on an SSD off 11.2 U1 (coming from mirrored USB sticks). I rolled back a week ago after the U2 SMB issue hit me. I had the SSD lying around for a while and decided to do the move today. So a clean install and an upload of the saved config brought me back to 11.2U1 but I noticed some jails not starting properly. As VNET issues were another reported issue I did the upgrade to 11.2U2.1 and started noticing this issue.
I also also noticed that during the "unresponsive" menu items I managed twice to have the system reboot itself while I was clicking in the menu structure (using Firefox current).
I checked open issues in Redmine but did not find this one yet (happy to be corrected).
Note that I did not change any settings moving from 11.2U1 on USB to 11.2U1 on SSD and upgrade to 11.2U2.1 .
Update: I have four iocage jails of which three are pluginv2 ones, all the same version. Two of these plugin jails have the ip addresses that show up (.81 and .86). I also have an older warden jail. All have fixed ip addresses.
Update2: The two "offending" jails do not have the VNET feature enabled. They were working before the reinstall as stated above. Enabling VNET on one of them (stop jail, enable VNET, start jail) removes the ip address from the console list and the Dashboard but breaks network access ... Disabling VNET restores access and brings the ip address back into Dashboard and console.
I noticed that the ipv4 default route is not set for these jails. Enabling VNET and setting the default route removes the ip address from console and dashboard but does not restore network access to the jail.
Dell T20
Intel Xeon CPU E3-1225 v3
24 Gb DDR3 ECC
3 x 3 TB SATA harddisk
1 x 240 Gb SSD