Previously, I have encountered the similar issue after upgrading Firefox to version 37.0.1.
Here's the link of the question posted: Unable to access OEM 11g after upgrading to Firefox ver 37.0.1
I applied the suggested workaround
Set Firefox's about:config setting security.tls.version.fallback-limit to '0'. It worked for Firefox version 37.0.1 however, yesterday my firefox was updated automatically to verson 39.0 (I have since disabled the auto update). Everything broken again.
Working around no longer fix. Not sure what Firefox has done with the new release.