The Mellanox ConnectX-4 / ConnectX-5 drivers are not automatically loaded by the installer. To perform a network install using a ConnectX NIC the driver must be loaded manually.
During install, escape (ESC) to the loader prompt when you see the Welcome to FreeBSD Beastie menu and load the kernel and the following modules for Mellanox ConnectX-4/5 Ethernet support:
load boot/kernel/kernel load boot/kernel/mlx.ko load boot/kernel/mlx5.ko load boot/kernel/mlx5en.ko
If this method fails for some reason, during install excape to a shell before network configuration and run, "kldload mlx5en.ko".
After install, add the following line to /etc/rc.conf to load the modules automatically after mounting local disks:
kld_list="mlx mlxfw mlx5 mlx5en"
Please refer to the man page for further details or options: