Debian IPv6 Network Manager

Intro

On Debian 12 or more specifically Raspbian 12 Bookworm whenever I created a static IPv6 address router advertisement would cease to work.

I could not find a solution while using network manager, so I decided to remove it. This solved my problem.

If you are doing this on a remote system it can be done in the following order as not to loose connectivity to IPv4 or IPv6.

Configure Static IPs

vi /etc/network/interfaces

auto eth0
iface eth0 inet static
address 192.168.1.1/24
gateway 192.168.1.254


iface eth0 inet6 static
address 81b9:f2a7:449b:cf9e:3d2f:4f65:ec96:7eba/64

Create Network Service

vi /etc/systemd/system/bring-up-eth0.service

[Unit]
Description=Bring up eth0 interface
After=network.target

[Service]
Type=oneshot
ExecStart=/sbin/ifup eth0

[Install]
WantedBy=multi-user.target

Enable Service

systemctl enable bring-up-eth0.service

Remove Network Manager

apt remove --purge network-manager
apt autoremove

Reboot

reboot