Between 5AM and 5:30AM we saw a reasonable number of BT SoGEA lines drop for around 100 seconds and reconnect.
They only dropped off once, but over a period of around 30 minutes we saw a few hundred drop and reconnect. As far as we can see the only common factor is that they are BT SoGEA lines. We don't have any planned work notifications for work on this scale, and the sites are dotted around the country.
These lines were migrated from VDSL to SoGEA two days ago and we suspect this could be a normal, automatic, DLM resync event.