Your hub is in WPS mode

BT Smart Hub 2 - WPS Button Flashing Blue 

How to fix problem:

Press the Wi-Fi Protected Setup (WPS) button on your hub to reconnect. You must do this within two minutes of your hub flashing.
If you have a WPS button on your computer or device also press this.

Your hub will return to normal mode with no flashing light after a few minutes. If your hub flashes red you didn't reconnect - 
give it a few minutes and try again.

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