My buddy called with a problem with his router.
Linksys vpn 4port router. (not sure of exact model)

Everything worked fine before last weekend... "the router just stopped working"...

I'm in the area... so I stop by to troubleshoot.

He could get his PC to access the internet without the router... but not with it.

He could get other PCs to access the internet with the router... but just not one PC.

I look at the config of the router and see its not getting a WAN ip. The MAC had been reset to 00-00-00-00-00-00. So, I click on the clone mac address so it can access the internet. I copy down the MAC that it cloned. I look at the PC that can't access the internet and notice that they have the SAME MAC address. Both devices having the same MAC were causing a conflict.

Why would it clone that PC's mac when its just a host on the network?
Shouldn't it clone the MAC of the cable modem?

I put a second NIC in the PC and all was fine...

Just had me a bit confused. But I rarely work with cable... (Comcast)

Any insight?