I have 4 computers connected by cables via a D-Linkdsl g-604t router modem and have been getting very low download speeds 0.3 to.06 meg. With only my main computer turned on Igot 1.1 meg, with the other 3 computer cables disconnected from the router I get 4.0 meg. Then3.04, 2.82, as I reconnect the turned off computers, then back to just mine connected back to3.3 then 3.09, 2.55, 2.193 as I go back to 4 computers connecfed to the router, but still only one turned on. All this over a time of 22 minutes, can some one tell me why

Try connecting your main computer directly to the cable modem bypassing the router, and run an internet speed test several times to get an average speed.

Call your provider and ask them to check your internet connection from their end.

Try updating the router's firmware.

Here is an excellent website for help with the major internet providers, router models, etc.

You can also check your internet download and upload speed test here http://www.ip-details.com/internet-speed-test/ at free of cost.