OVH VPS – IPv6 Reference Configuration

This page describes the correct and production-proven IPv6 configuration for OVH VPS (as of 2026).

The guide is provider-specific (OVH) and based on real-world operation, not on theoretical IPv6 best practices.

Tested with:

• Debian 11–13
• Ubuntu 20.04–24.04
• OVH VPS (KVM)

• Each OVHcloud VPS server is delivered with an IPv4 address and an IPv6 address.
• However, only IPv4 is configured by default. If you need to configure IPv6, it has to be set up manually on your system.

NOTE:
This documentation is intended for experienced administrators.

Make sure you fully understand every configuration line before applying it.
IPv6 and networking parameters are environment-specific (provider, routing, firewall, VPN).

Do not use blind copy&paste.
Always adapt addresses, prefixes, interfaces and gateways to your own setup.

OVH does not route real Layer-2 IPv6 prefixes to VPS instances.

This means:

• There is exactly one global IPv6 address
• This address is not on-link
• Neighbor Discovery works only via the gateway

Correct model:

• IPv6 address with /128
• Explicit gateway (usually `…::1`)
• No SLAAC
• No Router Advertisements
• No connected `/56` or `/64` prefixes

Important: Using `/56` or `/64` directly on the interface is wrong on OVH and will eventually lead to IPv6 blackholes.

• IPv6 address: `2001:41d0:XXXX:YYYY::ZZZZ/128`
• Default route: `::/0 via 2001:41d0:XXXX:YYYY::1`
• No RA dependency
• No on-link prefixes
• Reboot-safe
• VPN interfaces (e.g. WireGuard): routing only, no DNS

• systemd-networkd enabled
• Netplan in use
• Cloud-Init networking disabled

mkdir -p /etc/cloud/cloud.cfg.d
echo "network: {config: disabled}" > /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg

Create the file, for example:

/etc/netplan/60-ovh-ipv6.yaml

network:
  version: 2
  ethernets:
    ens3:
      dhcp4: true
      dhcp6: false
      accept-ra: false
      addresses:
        - 2001:41d0:XXXX:YYYY::ZZZZ/128
      routes:
        - to: ::/0
          via: 2001:41d0:XXXX:YYYY::1
          metric: 100
          on-link: true
      mtu: 1500

Set permissions:

chmod 600 /etc/netplan/60-ovh-ipv6.yaml

Apply (remote-safe):

netplan generate
netplan try

ip -6 a
ip -6 r

Expected result:

inet6 2001:41d0:XXXX:YYYY::ZZZZ/128
default via 2001:41d0:XXXX:YYYY::1 dev ens3 onlink

Many older OVH images still use ifupdown + cloud-init.

The active configuration is usually located here:

/etc/network/interfaces.d/50-cloud-init

mkdir -p /etc/cloud/cloud.cfg.d
echo "network: {config: disabled}" > /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg

Edit the file:

nano /etc/network/interfaces.d/50-cloud-init

Wrong (typical OVH default):

iface ens3 inet6 static
    address 2001:41d0:XXXX:YYYY::ZZZZ/56

Correct:

iface ens3 inet6 static
    address 2001:41d0:XXXX:YYYY::ZZZZ/128
    gateway 2001:41d0:XXXX:YYYY::1

No `post-up route add` constructs are required.

ifdown ens3 --exclude lo
sleep 1
ifup ens3

ip -6 a
ip -6 r

Expected:

inet6 2001:41d0:XXXX:YYYY::ZZZZ/128
default via 2001:41d0:XXXX:YYYY::1 dev ens3

If cloud-init is not in use:

auto ens3
iface ens3 inet dhcp

iface ens3 inet6 static
    address 2001:41d0:XXXX:YYYY::ZZZZ/128
    gateway 2001:41d0:XXXX:YYYY::1
    mtu 1500

WireGuard should provide routing only, not DNS.

Recommended peer configuration:

[Peer]
AllowedIPs = 192.168.0.0/16, fdXX:YYYY:ZZZZ::/48|56|64

Do not use:

• `::/0`
• `0.0.0.0/0`
• `DNS=`

• [ ] IPv6 address `/128`
• [ ] Default route via `…::1`
• [ ] No connected `/56` route
• [ ] Cloud-Init networking disabled
• [ ] Reboot test completed
• [ ] VPN without default tunnel

OVH IPv6 works reliably – > if it is operated the way OVH actually routes it.

Links: OVH IPv6 Configuration