Lag and player disconnects more frequent all of a sudden?

On an interval of less than a minute to about every 5 minutes, players are getting disconnected after lagging (timing out), but it doesnt always happen to everyone at the same time, or to everyone period. Sometimes it comes in waves that knock everyone off though. I've tried mostly everything including looking at all the plugins. I was experimenting with running 2 servers from the same computer after this started happening, and it affects them both at the same time. I think there may be something wrong with my internet, but I've rewired it into the router/modem many times and restarted it several times as well. Any ideas??