Comment by icebraining

Why should my fridge have a FQD name? What purpose does that serve?

To allow you to create a signed certificate to authenticate it?

Why install a firewall in each device if you can install one on the router that works for everything?

Having an FQDN doesn't mean you need to install a firewall on your device. You can still use the router's, and even prevent any inbound connections from the WAN to the device.