I have experienced something odd with my Truenas mini XL running 21.08.
I have network interface eno1 setup as DHCP, given a static IP on my UniFi network. The other interface, eno2, is setup without DHCP, but with a fixed IP on another network.
When the mini is booted, eno1 correctly grabs the static IP handed out by the DHCP server, 192.168.1.20.
When I then try remove the static IP of eno2, and the network is resetting, eno1 suddenly switches to the IP 192.168.1.195, for no good reason.
After a reboot, it switches back to the DHCP static IP, 192.168.1.20.
Anyone else seeing something like that?