Strange 100% packet loss spike

Turned on my BQM yesterday,. as I recently upgraded to 10mbs upload. The graph:

My Broadband Ping

Ignore the spikes between 6pm -> 8pm, that was me messing about with router settings.

What is the spike at about 1:30am? My router logs show no PPPoE disconnection, and I haven't got access to the BT Openreach 'blackbox' vdsl modem, so can't see it's logs.

Ideas? Does the firebrick get rebooted?

Nick

There's no corresponding effect in my BQM graph for today.