Using the connect to server facility in the Files.app the response is "There was a problem connecting to the server. Check the server name or IP address, and then try again. If you continue to have problems, contact your system administrator."
"example.com" and "example.com:2078" return the same error. "
Example Domain" is rejected as invalid by the app. This is an SSL connection.
Also, connecting in Safari is successful on the phone.