This is how I do it from a " Terminal" session on my Mac:
Fetch all pedalboards from Mod Device
scp -r root@192.168.51.1:/root/.pedalboards/*
Copy back/replace all pedalboards to Mod Device
scp -r *.pedalboard root@192.168.51.1:/root/.pedalboards/
Restart webserver afterwards
ssh root@192.168.51.1 systemctl restart mod-ui
Of course you can modify this for a specific pedalboard.
Note: The IP address may change weather you are connected through Bluetooth or USB.