From the README file under the WADEWebClient_R12_SP1
URL to access DE Web UI is
If you want to access DE Web UI using any other alias names such as localhost
or ip address or with domain name, access the above URL first with a valid login.
Only after you authenticate the logic of WEB UI using the above url, you can use URLs with alias name.
If you miss this step and access the URL using alias name first, you will encounter an error
"The login service is not available at the moment."