As noted in the documentation, all URLs are relative to this base URL. There is nothing posted at this URL.
Release : 20.3
Component : UIM - WEBSERVICES_REST
This behavior is to be expected. The URL Structure for the probe is described in the documentation:
To test the webservices_rest functionality, use any of the other documented commands. The commands should be appended to the base URL, for example:
If these and other commands work, the API is functioning properly.