I let someone setup a computer on my network for the pupose of using Kazaa Lite or something. I won't let trash like that on my computer. I think he set it so noone could download from him (empty folder, or just plain nonsense files.) This worked well for some time, until he made some changes. Not knowing what he was doing--though he, as a teenager, thinks he does--he made changes to help the download speed or sources, or some other nonsense. This was fine until. the next day when downloads and page loads were slow. Disconnecting the offending computer from the network, and resetting the modem and router, put it back to normal. Then, kicked him off the network for a week, even though "it wasn't his fault", and told him to fix the problem when he got back.
He said he doesn't know what did it, so we tested various settings, until he finally reset all configuration settings via some "program" ("hey kewl, here's a program that sets it backk to the defaults!") back to the defaults. Earlier today, download speeds were quite slow, that is, ~60 KB/s as opposed to the normal ~360 KB/s, and pages loaded slowly. At this point, i'm ready to ban him from the network, regardless of the reason.
However, there are two issues. One, yesterday the network slowed down nearly that much, though slightly faster, IIRC, ~90 KB/s, even without him connected at all. This never happened in my tests to determine which computer slowed it down. Two, why do i need to reset the modem and router? Perhaps only one is reuired, i simply do both because it works.
The network is simple. Comcast provides the high-priced service through a cable modem. A four-port router with DHCP provides the network. Connected to it are desktop, laptop, neighbor's desktop (light user), and this Kazaa box. Is Comcast playing games here? What else could it be?