Symptoms
When attempting to configure a shared virtual host IPv6 address in the WHM Basic WebHost Manager® Setup interface, you receive the following error.
Invalid Shared Virtual Host IPv6 Address value: "XXXX:XXXX::"(The range overlaps with another existing range: ipv6). This setting will not be updated.
Description
This error indicates that an IPv6 range that includes the entered address already exists on the server. The shared virtual host IPv6 must be a unique address that is configured on the eth device directly and not contained within an existing range.
Workaround
To configure a shared virtual host IPv6 that is contained within the desired IPv6 range, you will first need to reserve the address. To set the reserved range the existing range will need to be removed and re-added afterward. You can set a reserved IPv6 range inside the WHM IPv6 Ranged interface. By specifying the correct subnet, you can reserve a specific address or group.
For example, a /128 range like the following would reserve only a single address.
fe80::f816:3eff:fef1:1/128
While the following /116 would create a range consisting of the remaining entries for the last group.
fe80::f816:3eff:fef1:0/116
Once the IPv6 address has been configured on the eth device and reserved in WHM, you can add both the shared virtual host IPv6 and the IPv6 range.
For tips on getting started with configuring your IPv6 address, see the following article.