I used to be able to connect to VPN server using Safari, but after updating Java, it gets stuck at the "Testing Java compatibility. . . ." screen and I cannot establish a connection to VPN server.
There are known issues with selected VPN software that can't use Java 7. Contact your IT department or the VPN develper to see if there is an update yet. If not then you will have to revert to Java 6 as Apple outlined in Java for OS X 2012-006: How to re-enable the Apple-provided Java SE 6 applet plug-in and Web Start functionality.