I have two Realtek 2.5 Gbit Lan adapters is my new firewall computer.
But no network adapters are found during installation.
Is the hardware defective ?
Probably they are simply not supported by FreeBSD.
Hardware compatibility list:
https://www.freebsd.org/releases/15.1R/hardware/#ethernet
https://man.freebsd.org/cgi/man.cgi?query=re&sektion=4&format=html
I cannot find any 2.5G Realtek adapers in there, only 1G Realtek and 2.5G Intel.
You probably need the os-realtek-re plugin. Without a network connection, it is a little hard to install it, though.
I have realtek nics on two systems.
I am using arm64.
I compile the ports myself or fetch the package and manually install the driver.
realtek is supported by these ports:
https://www.freshports.org/net/realtek-re-kmod/
https://www.freshports.org/net/realtek-rge-kmod/
This is the one for arm64:
https://www.freshports.org/net/realtek-re-kmod198/
To bootstrap the process you could use a usb nic to get connectivity.
I have bought an Intel 82576 based dual port Lan card.