[BreezyDog]

The reason your bandwidth drops in the evening is because thats when EVERYONE gets home from work or school and fires up the computers. Your neighborhood cable network is shared bandwidth. When everyone jumps on you have less. If you had a dedicated T1 it would be all yours all the time. But thats only 1.54 Mbps up and down.

[ThePythonicCow]

When bandwidth drops like clockwork, in a big staircase like drop, and goes back up similarly, then that doesn't seem like simple contention for a shared network. I'd expect simple contention to be more erratic.

What ChildOfThe60s reports sounds more like an intentional throttling, presumably done in an effort to avoid the more painful affects of excess contention for limited resources, such as crashing switches and extreme delays for even low bandwidth traffic.