I happen to have been using a network monitor for the last 3-4 days checking against some specific sites. There are checks every 5-10 seconds being performed.I have not had any disconnect issues with the SKY service, although I do see a small 5% ish slowdown for about 1/2 hr to 1hr from time to time. I assume this is when SKY do some mtc work, or the traffic is busy on my exchange.
Does not explain your issue, which could be some form of upgrade, which we will never know. The question is "overall all" is the service working and if not I would raise a service ticket, as is working here.