I am having trouble connecting my RCA dcm425 with a dynex 10base-t ethernet hub to two devices at once. Comcast said I should be able to connect two devices at once but I can only connect one at a time. Whichever one I plug into the switch first is the one that can access the internet.

SOURCE: My connection fall

Please describe the leds in front of the modem which led lights or blinking ?

SOURCE: RCA DCM425 modem ethernet connection won't work

The setting for the Computer 1, use the network connection wizard to automatically configure the modem to work as a server station. Next, set the IP number manually and the DNS at automatic or is given by your ISP. Now the Computer 2 (workstation) should be connected to a Hub/Switch. The same, go to network connection wizard and select the appropriate connection setting, there are view samples for the connection types so explore them. After the setup, try loading your internet browser.... When done, it should work fine. Keep me posted for any problems.

SOURCE: rca dcm425

Try this site - they have RCA425 USB drivers posted
http://helpdesk.powergate.ca/index.php?id=19

SOURCE: DHG535-2 and LAN switch issue

It sounds like the LInksys that they replaced was also a router. A router will route packets to multiple pc's that are connected to it. The cable modem just sees the router as 1 pc. When you use a switch, the cable modem will see all of your PC's. and Comcast just allows 1 pc. You will need to buy a router to use more than 1 PC which will be cheaper than using Comcasts Home Networking service which will network up to 4 pcs

SOURCE: trouble connecting netgear wireless router to rca modem DCM425

First try connection the Yellow ethernet cable from the rca modem to your computer's network connection. If you get a connection this way, then your modem will work with a ethernet cable. If not, then call Comcast for help. The modem ethernet out to computer port must be connected to the wan line of the router. Then you can connect an ethernet cable from your computer network connection to one of the 4 ports of the router. For wireless connections you must set up the router and wireless adaptor with the same settings to connect. Follow the routers directions.
Good Luck