After installing and enabling the Symantec Protection Engine (SPE) User Interface (UI) per How to enable the console with Protection Engine for Core server with user interface mode, the interface hangs while loading Java. The progress bar stops halfway. No Java security prompt is displayed.
Certification revocation checks are timing out, preventing access to the site.
The server does not have access to the Internet
Disable the certificate revocation checks in the Java Advanced Security settings. These checks will always fail if the server does not have access to the OCSP or CRL protocols over the Internet if Java is set to perform these checks. As a result, Internet Explorer will time out attempting to load the SPE console Java Applet.
After configuring the above settings, Java will no longer attempt to perform certificate revocation checks on the code signing and TLS certificates used for the SPE console, and the Java applet should load much more quickly.