I will answer here as the original author seems not to be here any more. But i got the same problem.
ddclient is configured from the nextbox installation.
The ddclient.conf contains:
protocol=dyndns2
daemon=300
use=cmd, cmd=’curl https://checkipv4.dedyn.io’
ssl=yes
server=update.dedyn.io
login=’hostname.dedyn.io’
password=’xxxx’ (should be valid)
hostname.dedyn.io
The v6 Adress is in the account, the v4 Adress is missing.
If I enter the v4 Adress manually it works for some minutes, but regardless how much ttl I enter it is gone after some minutes. Most likely after the next time the demon was running on the nextbox.