Copy the relevant files from your old instance to the new one.
saves - stores your worlds.
local - stores your FTB Chunks map/waypoints.
options.txt - stores your graphical, keybind, and other settings.
servers.dat - for multiplayer, stores your saved servers.
The initial steps are the same for all hosts.
startserver script and follow the installation instructions.world folder.world to the new server folder.server.properties, you can copy them also.
configsdefaultconfigskubejslibrariesmodsserver-setup-config.yaml, you should also:
server-setup-config.yamlserverstarter.lockstartserver.batstartserver.shserverstarter script.