try a soft reset… You won’t lose any devices, automations, etc.
Disconnect the power cable from the Hub (2015 / v2 hub only - remove all batteries as well) .
Make sure ethernet is connected
Using a pin or a small tool, hold down the reset button on the back of the Hub
While holding down the reset button, reconnect the power cable to the Hub
Continue holding the button for about 15 seconds
When the LED on the front starts flashing yellow, release the button
The hub will re-download the latest firmware and the Hub’s LED will go through several different colors and patterns. When it’s done, the LED will return to solid green. This can take 15-20 minutes depending on your internet speed.