My router is a level one WBR-6011: http://global.level1.com/Wireless/WBR-6011/p-835.htm
My modem is Cisco 2100: http://www.cisco.com/web/consumer/support/modem_DPC2100.html#~userguides

When I run the modem straight to the desktop I have internet. When I add the router, I lose my internet to the desktop computer which is wired. The router works fine when it's connected, the problem is there's no internet. Again, with no router I have internet, with the router, no internet. I assume for both CONFIGURATIONS you are using the ethernet port on the modem & not the USB port?Yes, I'm using the ethernet port on the modem. 1. Bad cable from router to modem.
2. WAN port on router is dead.

I assume the yellow port (WAN) on the router is the one you are connecting to the modem?
I started this thread the last time I had a problem with the router which was the 13th, one week ago. Since that time the router has worked fine. But last night it happened again. I didn't call the cable company but RAN my modem straight to my desktop and the internet worked. I tried re-powering the modem and router in all DIFFERENT orders and combinations many times without results. Now, 12 hours later, I turned everything on and it's all working fine now with the router connected. On one occasion when I was on the phone with the cable company, they said something about the network not seeing my router.

This is a crazy intermittent problem happening at about once a week. Any THOUGHTS? If I buy an ethernet y-cable and run that from the modem-one to my desktop, one to the router, would that do anything? I add that because when I bypass the router I get internet.I assume the yellow port (WAN) on the router is the one you are connecting to the modem?Quote

I assume the yellow port (WAN) on the router is the one you are connecting to the modem?