If application refuses to connect then it can be due to multiple reasons:
Application is shut down due to some reason which needs to be checked inside the logs. You can bring it back up by running the following commands on the VM instance. In the majority of cases this will solve the problem.
Download error - The specified key does not exist
Sometimes, when files are ingested directly into the bucket (without using the file manager), the front-end gets out of sync. In that case, please follow these steps and see if you are able to download.
Click the Group-Folders
Press the 3-dotted button
Click "Refresh Folder..."
Wait until the process is complete (second diagram).
Try the download again.
Docker service is not running
Sometimes the software of docker is updated on the host machine and it does not start the docker. Run the following command to start it.
sudo service docker start
Still finding issues...
Remove the previous installation by going to the deployment manager and removing the deployment. Once it is removed then reinstall the software from the marketplace using the same steps.