The black screen when connecting from an external source sounds like a firewall issue. You should follow all the steps in this document, https://communities.vmware.com/docs/DOC-14974, to resolve that issue.
What kind of certificate error do you get when connecting internally? FWIW the View client with local mode only needs to be used if you are going to utilize local mode. Local mode is the ability to download and run a desktop on local resources instead of geneating a session from the server.