Why Can't I Access Websites Using IPv6 Addresses After IPv4/IPv6 Dual Stack Is Configured?

Symptom

You have enabled IPv4/IPv6 dual stack for an ECS, but the ECS cannot access websites using IPv6 addresses.

Troubleshooting

• Check whether the IPv4/IPv6 dual stack is correctly configured and whether the dual-stack NIC of the ECS has obtained an IPv6 address.
• Check whether the obtained IPv6 address of the dual-stack NIC has been added to a shared bandwidth.
• If the ECS has multiple NICs, check whether policy-based routes have been configured for these NICs.

Solution

• When you buy an ECS, select Automatically-assigned IPv6 address for Network.
  

  If an ECS is created from a public image:

  Before enabling dynamic IPv6 address assignment for a Linux public image, check whether IPv6 is supported and then check whether dynamic IPv6 address assignment has been enabled. Currently, all Linux public images support IPv6, and dynamic IPv6 address assignment is enabled for Ubuntu 16 by default. You do not need to configure dynamic IPv6 address assignment for the Ubuntu 16 OS. For other Linux public images, you need to enable this function.

• By default, IPv6 addresses can only be used for private network communication. If you want to use an IPv6 address to access the Internet or want it to be accessed by IPv6 clients on the Internet, you need to add the IPv6 address to a shared bandwidth.

  If you already have a shared bandwidth, add the IPv6 address to it.

• If an ECS has multiple NICs, the primary NIC can communicate with external networks by default, but the extension NICs cannot. To enable extension NICs to communicate with external works either, you need to configure policy-based routes for these NICs.