Hi,
I have tried to create a cron job that do "Dynamic DNS update" every 5 minutes.
When I look in the log I see no sign of the job executed.
Did you hit "apply" in the cron GUI or reboot to make these settings permanent?
Note that 5 minutes may get you temporarily blacklisted with your provider.
Cheers,
Franco
Sorry - did not see your post.
A reboot fixed it.