TDV server service may fail to start and TDV studio may throw the following error when trying to connect to TDV Server:

Failed to connect to http://localhost:9400/cdms/webapi; nested exception is: 
java.rmi.RemoteException: HTTP transport error: java.net.ConnectException: Connection refused: connect; nested exception is: 
HTTP transport error: java.net.ConnectException: Connection refused: connect [Log ID: 5aac08d7-d505-4ba4-98c3-e4ea5d18ec25]

One of the reasons for this behavior is the lack of access for logs folder (located at: <<TDV Install Dir>>\logs]\) for the account that is running the TDV Server. To resolve this issue, ensure that the service account running the TDV Server has read & write access to the logs folder.

Note: It is always a good idea to archive all the logs after stopping all TDV services, then start the TDV services again. TDV will regenerate all the log files again with correct permissions once it is successfully started. If needed, take a backup of the logs before purging these.