Found the online help file, its ID number is 5838. This provides a few scenarios and resolutions.

Depending on the state of the xPanel and iPad will depend on what needs to be done to resolve. If only xpanel doesn't work yes this may be an SSL issue and it needs to be turned off, Text Console "SSL OFF" then reboot. If both xPanel and iPad are experiencing the same problem then there is likely an issue with the boot and you need to complete the program recovery procedure and do an initialize and restore on the unit to clear it. I had to do this once and it took a day for the hub to return to a working state (so far no issues since).