My home network consists of a Comcast modem, connected to a Linksys WRT330N wireless router, and then to a Linksys SD2005 switch.
The last few days my internet speed has been like dial-up, and actually not as fast as dial-up. I have rebooted everything, computers, modem, router, and switch, many times and didn't help.
I decided to do a process of elimination, so I hooked the modem directly to a computer, and to my amazement my speed was back.
Then I connected the modem to the router, and then one computer to the router, nothing.
Then I connected the modem to the switch and then to one computer, and it again worked connected like that, but that is all I can connect to the switch is one computer even though it has 3 other ports