Change how debian network is configured.

manifests/public_ip.pp

@@ -39,6 +39,15 @@ class lysnetwork::public_ip {
     }
     'Debian': {
       package { 'resolvconf': ensure => installed }
+      # https://forge.puppet.com/modules/example42/network
+      # Debian seem to require a separate interface rule per
+      # interface, per network stack.
+      network::interface { "${iface}v6":
+        enable    => true,
+        interface => $iface,
+        ipaddress => "2001:6b0:17:f0a0::${last_octet_16}",
+        gateway   => '2001:6b0:17:f0a0::1',
+      }
     }
     default: {}
   }