There is an operation in the SOAP web service called ConnectionInfo. In recent versions this has been deprecated there is, however, an alternative. The purpose of ConnectionInfo is to return information about the currently connected user, this is now discoverable via the ObjectStringSearchSelect.
How to get the current connection
The C# code below demonstrates using the ObjectStringSearchSelect operation to find the current user and fetch their Uri. Of course the Fetch could also be used to retrieve any other Location property.
TrimRequest request = new TrimRequest();
What is a .Net Error?
It can be the case, especially on a new installation of the SOAP web service, that the .Net framework is not correctly configured. This might result in an error a little like the one below.
Testing the connection
While it is possible to test the web service via a browser it is only possible to do this from the actual server machine. If you are not able to connect directly to the server you may wish to use this simple app to check if the web service is actually running and that you can authenticate. You can experiment with authentication and might see an error like this: