Explanation

This article describes how to set up IPv6 on Proxmox.

1. Add IPv6 configuration to /etc/network/interfaces

Edit the /etc/network/interfaces file and add your IPv6 configuration.

iface vmbr0 inet6 static
address IPv6_Addresse
netmask 64
up ip -6 route add IPv6_Gateway dev vmbr0
up ip -6 route add default via IPv6_Gateway dev vmbr0
down ip -6 route del default via IPv6_Gateway dev vmbr0
down ip -6 route del IPv6_Gateway dev vmbr0

if you have done that, save the file.

2. Add IP and FQDN to /etc/hosts

and as next step edit the /etc/hosts file, and add your IP and the FQDN.

IPv6_Addresse FQDN Hostname

(Example "2001:4ba0:ffa4:1:beef::1 mail.domain.tld mail")

if this is entered correctly, save the file.

3. Add nameserver to /etc/resolv.conf

Open the /etc/resov.conf file and add the IPv6 name servers there. 

nameserver 2001:4860:4860::8888
nameserver 2001:4860:4860::8844

4. Edit sysctl.conf

Run the following command to edit the sysctl.conf file: 

sysctl -w net.ipv6.conf.all.forwarding=1

5. Restart server

Once everything is complete and successfully set up, reboot your system. IPv6 should now be working.