[Blind-sysadmins] BT business hub logs for turning on and off

Hi All, I am looking at a BT business hub here in the UK and I wanted to find out when this router has been manually turned off and back on again. I have just reviewed the event logs, but there does not seem to be any clear indication of this information. Does anyone have any thoughts on how I can find this information? Kind regards, Chamandeep Singh Grover