How to apply the dynv6 DDNS Server to DD-WRT?

In Google Chrome, it can work! The IPV4 can be updated.
https://dynv6.com/api/update?hostname=(HostName)&token=(UserName)&ipv4=auto

In DD-WRT Url, it can connect to the sever but the ipaddress cannot be updated. I would like to know how to setup!

DYNDNS Server = dynv6.com
Username = password
Password = login = none
Hostname = Hostname

URL = /api/update?hostname=(HostName)&token=(UserName)&ipv4=auto

Thanks!

Error: 422