Simple task: I've assigned a V6 address to a debian9 box, but its not applying to the interface on reboot. The V4 address is applying. If i assign it manually using ip -6 addr add <ipv6address>/<prefixlength> dev <interface>
then it works fine. Here's a copy of my /etc/network/interfaces config
'# The loopback network interface
auto lo
iface lo inet loopback
iface lo inet6 loopback'# The primary network interface
allow-hotplug eth0
iface eth0 inet static
address 10.190.xxx.xxx/26
gateway 10.190.xxx.xxx
up route add -net 10.100.xx.xxx/32 gw 10.190.xxx.xxx dev eth0
# dns-* options are implemented by the resolvconf package, if installed
dns-nameservers 8.8.8.8 4.2.2.2iface eth0 inet6 static
address 2607:f0x0:xxxx:ac::20
netmask 64
gateway 2607:f0x0:xxxx:ac::2
ifup --force eth0
from an shell with root privs. Tell us the error.RTNETLINK answers: File exists ifup: failed to bring up eth0
ifdown --force eth0
. Might also need to try commenting out your ipv4 section temporarily, and trying to down+up the interface. The settings are applied in order and any failure will immediately abort.RTNETLINK answers: No such process RTNETLINK answers: Cannot assign requested address