Oh! I see what you are saying. I missed that your off command was a switch, sorry. Change this:
platform: command_line
switches:
switch_nas_off:
command_off: "ssh -l sshd 192.168.1.30 'sh /usr/sbin/shutdown.sh'"
command_state: binary_sensor.nas
friendly_name: "Switch Off NAS"
To a shell command.
Something like this (no idea it it will work like this):
shell_command:
switch_nas_off: "ssh -l sshd 192.168.1.30 'sh /usr/sbin/shutdown.sh'"
You will probably need to read this:
Though if it is working for the switch, it should work for the shell command.
Then this part of the WoL switch will be valid:
turn_off: command.switch_nas_off # used to turn off the switch
You will then have created one entity switch.nas and one service command.switch_nas_off, rather than two entities.