Add network connectivity support to initrd. The network may be configured using the ip kernel parameter, as described in the kernel documentation. Otherwise, if networking.useDHCP is enabled, an IP address is acquired using DHCP.
You should add the module(s) required for your network card to boot.initrd.availableKernelModules. lspci -v | grep -iA8 'network\|ethernet' will tell you which.