The Dual-Path Communication Failure - Cellular trouble condition indicates the cellular radio is unable to communicate through the cellular network, but the system is still communicating through the broadband network.
If this message has only been displayed for a few minutes, there may not be a problem. The cellular radio is likely trying to connect to the cell network currently. If this has been displaying for longer than about 15 minutes there may be something else going on. Ensure that the Hub is not within 5 feet of any large metal or electronic objects that could be causing cellular interference and relocate if necessary.