The TPL TL-ER7206 supports Custom DNS for its Dynamic DNS service
But, I cannot get that service to change from "Offline" to "Online"

The example I used came from the Dynu "IP Update Protocol"
http://api.dynu.com/nic/update?username=[USERNAME]&myip=[IP ADDRESS]&password=[PASSWORD or MD5(PASSWORD) or SHA256(PASSWORD)]

Their format of the "Update URL" requires three variables: [USERNAME], [PASSWORD] and [DOMAIN] with Dynu's URL to update the record

These 3 variables are supplied in their "Custom DNS" web form that is filled in with the details:
Interface: WAN or WAN1
Account Name: my_account_name (aka: [USERNAME])
Password: my_api_passcode (aka: [PASSWORD]) - I've also tried the API Key
Domain Name: my_domain (aka: [DOMAIN])
Interval Mode: Fixed
Update Interval: 1 day

The "Update URL" I'm using is:
http://api.dynu.com/nic/update?username=[USERNAME]&group=[DOMAIN]&myip=[47.141.10.36]&password=[PASSWORD]

I've tried changing the Password between my Dynu account password and the API Key

Any clues where I'm going wrong?