Join Date: Apr 2019
Location: Middle OH, USA, Earth
I lost power and internet for 5.5 hours a couple of weeks ago, and internet only for a few hours overnight a couple of nights ago.
My router assigns IP addresses to my household devices. The router is connected to a UPS to eliminate small power blip problems, and a house generator automatically started up and ran for the duration of the power outage. Neither event caused issues with the JB. I would assume, though I haven't tried, that if the JB has power you can connect to it with your phone, or other device, to control it when it isn't connected to anything else like you do for initial setup.