Pipe drop?

[#1]

Did BNG01 just drop?

[#2]

I really don't think so, those are just graphing glitches, presumably the graphing system fails to obtain the number of users at that time, so there's a gap in the graph.
If all users did get kicked off a gateway, they wouldn't all instantly reappear back on the gateway shortly later. The number of users on that gateway would increase more gradually (see attached image).

[#3]

Yep, false alarm.
Although it looks like there was a blip around 2am. Likely the result of BT maintenance.

[#4]

Did a lot of users fall off ptn-bng01 a little while ago? And the users got picked up by all the other gateways?

[#5]

I think we did have a disconnection in the afternoon, yes.