I am sharing cable using a di-704 router. I have a pc and xbox on that router. Ihave a connection from the 704 going into a di-604 router 50 feet away connected to its wan port. Then i have 2 pcs there and then another 50ft cable going to a switch with 3 pcs. All pcs receive internet. However, None of the pcs behind the second router(604) are able to see pcs connected directly to the first router(704). For example, i can not ping the first router at all. Both routers use dhcp but there ip pools do not conflict, which is why the internet works great on all. Can i disable the firewall completely in the 604 router or something similar? The dlink people say that i can not use the 604 as a switch unless i use a crossover cable. Seeing how i am 50 ft away, i can use a crossover cable. Any suggestions would be helpful.

You have to the function that turns enables you to change the device from a gateway (where is blocks incoming traffic on the WAN port) to just a basic router (where processes requests from either side). Look at the documentation that came with the router, or check D'Link 's (I assume) website. If you have the ports available, just uplink the switch ports on the 604 to the 704 instead of connecting 704 to the WAN port on the 604 (if I am reading your setup properly). You can either connect a straight through cable from a regular port of one device to the uplink port of the other device, or connect a crossover cable from a regular port to a regular port on the two devices. Catagory 5 cable is good for 100 meters, which is a little over 300ft, whether it is crossover or straight through, so distance is not an issue.

What Analyst suggests in the second paragraph will work but you will need to turn off DHCP on one of the routers so the PCs will all be in the same subnet.

FredF is correct, I missed that.