It still fails with latest iso (xcp-ng-8.3.0-20250606.2.iso) on Dell R770 and Broadcom 57508 100GbE QSFP56 Dual Port Adapter, PCIe Full Height
See post here
By the way, it works ok with 8.2.1 iso
It is in the same place in XO. Network tab of the host.
Change the Mode from None to Static (or DHCP). This should get you a pop up to enter the address, netmask, etc.