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For some reason I wish to connect the WAN port and the LAN port on a router to the same hub and make the hub is connected to both networks, the Internet and a private network. Below is a diagram of the network configuration I'd like to build.

A hub is connected to the Internet, two PCs, and a router with NAT. The WAN port of the router is connected to the hub and has an IP address of The LAN port of the router is connected to the same hub and has an IP address of PC 1 has an IP address of PC 2 has an IP address of, and its gateway address is

I tried this and it didn't work as expected. PC 1 has no problem, but PC 2 cannot connect to the Internet. When I ping from PC 2, all packets are lost. It works well when PC 2 is connected directly to the router.

What's the problem with the network configuration above?

share|improve this question
Run arp -a on PC 2 and see if the MAC corresponding to is your router's MAC. There could be another on the internet side. – Nov 17 '12 at 18:37
I did and there was an incorrect MAC address, so I manually changed that to my router's MAC. Still diconnected. – C. Lee Nov 18 '12 at 2:07

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