A new network card needs to be installed in the ggRock server.
Shut down the ggRock server.
Physically install the new network card in the ggRock server.
Power on the ggRock server.
Install network card drivers (kernel module) for Debian Linux (if required).
Plug network cable into the new network card.
Run ggrock-linux-configurator, selecting the correct network interface card from the list based on IP address.
Check that PCs boot successfully.
To revert these changes, simply re-install the old network card and re-reun ggrock-linux-configurator, selecting the old network card by IP address.