I am following this tutorial https://www.digitalocean.com/community/tutorials/how-to-enable-ipv6-for-digitalocean-droplets to enable IP6 in my existing droplet.I manage to enable the IP6 but for the configuration part when I run the command,

sudo nano /etc/network/interfaces

the output is(in the Putty),

"# This file describes the network interfaces available on your system

and how to activate them. For more information, see interfaces(5).

The loopback network interface

auto lo iface lo inet loopback

source /etc/network/interfaces.d/*"

this is not what it is shown in the tutorial,so the question is am I using the wrong command(I am a Window user so I am using Putty and also using Serverpilot)? and where do I insert the “primary_ipv6_address” and the “ipv6_gateway”?

Thank you.