SolusVM KVM VPSes do not have internet connection via IPv6: destination unreachable

Symptoms 

• SolusVM KVM VPSes do not have internet connection via IPv6. When pinging google.com via IPv6 the following error is generated:

  CONFIG_TEXT: ping6 ipv6.google.com
  PING ipv6.google.com(lax17s34-in-x0e.1e100.net (2607:f8b0:4007:802::200e)) 56 data bytes
  From 2001:db8:f61:a1ff:0:0:0:80 (2001:db8:f61:a1ff:0:0:0:80) icmp_seq=1 Destination unreachable: Address unreachable
  From 2001:db8:f61:a1ff:0:0:0:80 (2001:db8:f61:a1ff:0:0:0:80) icmp_seq=2 Destination unreachable: Address unreachable
  From 2001:db8:f61:a1ff:0:0:0:80 (2001:db8:f61:a1ff:0:0:0:80) icmp_seq=3 Destination unreachable: Address unreachable

• IPv6 is working fine on KVM node
• KVM slave node and the VPSes can reach each other via IPv6

Cause

IPv6 Forwarding is not enabled on the KVM Slave node.

Resolution

1. Connect to KVM slave node via SSH
2. Apply the steps 2, 4 and 5 from this article:
   How to configure the IPv6 on a KVM slave?