We observed IPv6 misconfiguration on Debian/Ubuntu configuration images. If you have troubles on it, please check file /etc/network/interfaces, you should see something like:
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto eth0
iface eth0 inet static
address 83.136.1XX.XX
netmask 255.255.254.0
gateway 83.136.106.1
iface eth0 inet6 static
address 2a02:29e0:2:6:1:1:XXXX:XXXX
post-up /sbin/ip -r route add 2A02:29E0:2:6::1 dev eth0
post-up /sbin/ip -r route add default via 2A02:29E0:2:6::1
With that configuration if you try to ping some destination you will get Address Unreachable error. To fix it, please adjust /etc/network/interfaces:
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto eth0
iface eth0 inet static
address 83.136.1XX.XX
netmask 255.255.254.0
gateway 83.136.106.1
iface eth0 inet6 static
address 2a02:29e0:2:6:1:1:XXXX:XXXX
netmask 64
gateway 2A02:29E0:2:6::1
IPv6 should be restored
