That is usually associated with the Hopfield neural data correction algorithm used in older modems (even if you bought it yesterday) on DSL, cable & satellite systems. It trains itself to correct expected errors on the line and after a while it starts to inference too much and gets slow. I just got in a new AT&T Uverse and it has 6 mbps internet channel capacity as well as 300 TV channels. I was lucky to be 200 feet from a light speed fiber box. This system rocks!just a tip for you guys with highspeed internet
about once per month I shut off my high speed modem
and my wireless router for about 3-5 minutes then
turn the modem back on and once reset and
reconnected I then turn on the router and let that resync.
you would be surprised at how much quicker your connection