Hetzner Cloud netplan configuration for IPv4+IPv6 (Dual Stack)

50-cloud-init.yml

# /etc/netplan/50-cloud-init.yml
# Ensure that other netplan config yml files in /etc/netplan/ don't interfere with this configuration

network:
  version: 2
  renderer: networkd
  ethernets:
    ens3: # (Primary interface, usually ens3 or ens33 on recent Ubuntus)
      addresses:
        - <Hetzner instance IP4>/32
        - <Hetzner instance IP6>::1/64
      routes:
        - to: 0.0.0.0/0
          via: 172.31.1.1
          on-link: true
      gateway6: fe80::1
      accept-ra: true # needs to be enabled!
      nameservers:
        addresses: # (Hetzner DNS servers)
          - 213.133.98.98
          - 213.133.99.99
          - 213.133.100.100
          - 2a01:4f8:0:1::add:1010
          - 2a01:4f8:0:1::add:9999
          - 2a01:4f8:0:1::add:9898

@strarsis hello! i'm trying completely disable ipv6 on Ubuntu 20.04 for my cloud instance,and I wrote in the sysctl.conf file such parameters
net.ipv6.conf.all.disable_ipv6=1 net.ipv6.conf.default.disable_ipv6=1 net.ipv6.conf.lo.disable_ipv6 = 1
Then I reboot my instance and ipv6 still enabled, only works if I use sysctl -p when instance online. blacklist ipv6 in /etc/modprobe.d/blacklist.conf not working either...Any ideas how to disable ipv6 for cloud instance?

@No0key it appears that there is also a Grub line (source: https://www.linuxbabe.com/ubuntu/disable-ipv6-on-ubuntu) Caution: I did not test/try this: GRUB_CMDLINE_LINUX="ipv6.disable=1" or GRUB_CMDLINE_LINUX_DEFAULT="ipv6.disable=1" (https://askubuntu.com/questions/1046057/disabling-ipv6-in-ubuntu-server-18-04)

@frennkie thanks for the reply. I've tried grub line and that not worked for me on ubuntu20.04 (can't connect to my server). I've found cause of my problem. If any ipv6 settings is used in your config file, ipv6 will be enabled. Since this pull request, networkd just ignores what in sysctl.conf. Solution that worked for me is remove all ipv6 configuration from netplan.yml.