Is this a supermicro board by chance?
See: TrueNAS Scale - Virtual IP Address - #8 by essinghigh
Something may have changed with Dragonfish, I don’t have anything on hand to test unfortunately, but generally enx* interfaces will be used for external devices, i.e. a USB Ethernet controller (Ethernet External)
See: systemd.net-naming-scheme(7) — Arch manual pages