Bandwidth dropping like clockwork every night around 7-8PM for ~2 hours

[FZE]

A week or two ago my cable modem started cutting out entirely every night around 7 or 8 PM - it could ostensibly send and receive packets but it couldn't hold onto a signal. In the last few days, it's stopped doing this, but around the same time I start getting massive bandwidth cuts for two hours or so. To get an idea of what sort of reduction we're talking, I ordinarily ping Google at around 35ms, but during these phases I consistently go over 175. Same in games, only worse.

I've tried resetting my modem, resetting my router, switching my router for another, all during these "blackouts", and I've ensured that I'm the only one connected to the network, all other systems unplugged and WiFi disabled. I've also checked using other systems and devices, the drop is across the entire network.

Any ideas as to what's happening?

[Mr Skeltal]

Do you have AT&T? I experience similar stuff sporadically. This has been happening for years.

[FZE]

I've got Insight, I think it only exists within a few states in close proximity, maybe Indiana and Ohio.