I own a Motorola SB6141 that I bought from best Buy yesterday and I'm having some issues with the LEDs. It says to turn on the computer, and the receive, send, and Online lights will flash, and then be solid. Mine, however, has only receive flash blew, and the bottom LED, link, is flashing orange. No send or online. They keep flashing. I already called Cox (my ISP) and they activated it or whatever. And calling ARRIS tech support didn't help either. I even tried taking out the cable as Ethernet cables and switching them out, and I get the same issue. What can I do?
I had a similar problem with a linksys about a year ago. If are able to log into the router's admin panel (your instructions should indicate how to do this, for me it was http://192.168.1.1). From the admin page, there should be a "configuration" option somewhere on the page. From there, click the "Reset All Defaults" option. Motorola's forums indicate this may take a few minutes. After that, try a power cycle just to be sure. Unplug the modem for about 30 seconds and plug it back in.
If that still does not work, I know you said you tried using different cables, but have you tried using a different port on the back? You may simply have a defective port if the other three still work.