i'm always trying the IP address of connection server to connect it, however the browser shows blank.
the knowledge base 2144768 did not solve my issue after i tried adding add locked.properties file to the config. folder and reboot.
EDITED (not enough coffee yet)... Firefox doesn't ship with it's own Flash, do you have adobe flash installed and updated. Otherwise try using Chrome which has it's own built-in flash plugin (pepperflash) after putting in the locked.properties.
Usually when you see that black screen the browser can't start the flash plugin.
honestly, the flash was enabled in the firefox, I checked it in the add-ons and tried to open the connection server administrator webpage in the browser again and again with caution.
I'll try to figure this out but for now it is truly an annoying and strange bug.