After almost a day of messing around with various configuration options for Java, Firefox and a few other browsers trying to get this thing to work again, rolling back to Java V8 121, whilst not an ideal solution, seems to have done the trick.

Java Plugin Firefox Mac

For anyone else using a Checkpoint SSL Network Extender on a Mac, I suggest not updating Java until they start supporting browsers other than IE again... https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk113410

Instalar Plugin Java Firefox Mac

Turning Java plugin on or off in Firefox web browser Enable or Disable Java in Firefox Beginning in Firefox version 52 released March 7, 2017, installed NPAPI plugins are no longer supported in Firefox, except for Adobe Flash. Some of the plugins that wil.