As Deputy said here https://community.tp-link.com/en/business/forum/topic/599332?replyId=1184858

Just allow users to fill username, password and hostnames directly to update url. It will be much more easier and faster way, instead off creating update url with [variables] then adding entries with username, password and hostname.

  @Hoamboy 

Must be something else going on here as its still not working for me from the UI on the ER605.

As stated, the login is exactly as entered into No-ips own DUC and that works ok, when the same update url is entered into chrome address bar, again it works ok and returns nochg XX.XX.XX.XX

but the information when entered into the ER605 UI just doesn't work.

The service status shows offline and the system log shows WAN [username] login no-ip server fail.

  @NX01 

As we said in the beginning of this thread - Custom DDNS shouldn't be required here as this service is natively built-into the Controller.

And it works perfectly fine for me if configured properly.

However, I can only confirm this for ER605 V2 and ER7206 both on latest stable firmware.

For ER605 V1 I can't say anything here - it is theoretically possible that there's a bug in the firmware.

Maybe @Hank21 and the DEV Team can test a NO-IP account on ER605 V1?