Using DynDNS API with Zone Keys

I have a Zyxel 3000Z which implements the DynDNS API (/nic/update?) with a custom option, so it should work with dynv6.

I’ve filled in as the server. Then /nic/update? in the request field (as per instructions I found for another service that implements the DynDNS api).

for the username, I’ve filled in the email address I registered with dynv6. For the password I’ve filled in the API key that I created for this zone. It’s not shown in the screenshot, but I filled in the hostname as host.myzone.mydomainname.tld, which I have registered in dyn6.


When I try from a Linux PC with curl, it works fine, regardless of what I fill in for the username; looks like that field is actually ignored:

$ curl '${IP}'

Anyone know what might be wrong? I’ve tried different values for the username since testing with curl, but still no luck on the router.