Yes, the connection URI for a [**default**](https://community.denodo.com/tutorials/browse/basics/2fs_index) installation is **//localhost:9999/admin** and the default username and password for connecting to Virtual DataPort Administration Tool is admin/admin.
In case of error during connection, I would perform the below checks to successfully [**launch**](https://community.denodo.com/docs/html/browse/7.0/vdp/administration/installation_and_execution/launching_the_virtual_dataport_server/launching_the_virtual_dataport_server) it from the Denodo Platform control center:
* Check if the Virtual DataPort Server is in **running** status and then ensure that username and password is correct.
* Check if the [**port number**](https://community.denodo.com/kb/view/document/Ports%20needed%20by%20the%20VDP%20Server?category=Operation) “9999” is not used by another application because this will block the Virtual DataPort Server to be started up.
* Check the **vdp.log** file located in “<DENODO_HOME>/logs/vdp” for logging events from the Virtual DataPort Server which will provide more information on why the error is thrown.
Additionally, if you have multiple network interfaces or if you are trying to connect to Virtual DataPort Server located on another machine then you need to configure [**RMI host**](https://community.denodo.com/kb/view/document/Virtual%20DataPort%20Connectivity?category=Operation).
Hope this helps!