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 network interface of the ECS has obtained an IPv6 address.
• Check whether the obtained IPv6 address of the dual-stack network interface has been added to a shared bandwidth.
• If the ECS has multiple network interfaces, check whether policy-based routes have been configured for these network interfaces.

Figure 1 Network interface details

Solution

• When you buy an ECS, select Automatically-assigned IPv6 address for Network.
  If an IPv6 address fails to be automatically assigned or the selected image does not support automatic IPv6 address allocation, manually obtain the IPv6 address by referring to Dynamically Assigning IPv6 Addresses.

  • By default, dynamic IPv6 address assignment is enabled for Windows public images.
  • Before enabling dynamic IPv6 address assignment for a Linux public image, check whether IPv6 is supported first.

    Currently, all Linux public images support IPv6. By default, dynamic IPv6 address assignment is enabled for Ubuntu 16. 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. For details, see Buy a Shared Bandwidth and Add the IPv6 Address to It.

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

• If an ECS has multiple network interfaces, the primary network interface can communicate with external networks by default, but the extended network interfaces cannot. To enable extended network interfaces to communicate with external networks, you need to configure policy-based routes for these network interfaces.

  If your ECS runs Linux, refer to Configuring Policy-based Routes for a Linux ECS with Multiple Network Interfaces (IPv4/IPv6).

  If your ECS runs Windows, refer to Configuring Policy-based Routes for a Windows ECS with Multiple Network Interfaces (IPv4/IPv6).