Cable modem from Charter

[Piru]

[EDIT]Removed some crap after rereading the original post[/EDIT]

Hm hm, it sounds like you need to reconfigure the D-Link router to get it working properly.

Unfortunately I have no experience with D-Link 704-P, but surely it should be able to handle DHCP from the cable, and static IPs for the LAN... I guess it's time to consult the D-Link manual or something :-) Keywords to look for: IP MASQ, NAT.

Once you get this going, you should be able to turn off the DHCP from the PC again (if desired).

[Piru]

Err, so that D-Link 704-P router isn't a router at all?

MAC addresses do not pass thru routers...

Anyhow, any decent router can do NAT, which nicely solves the problem.

[Piru]

@stopthegop

Oops. Right, you propose dropping the d-link there.

Yet, isn't this router a router? If not, what is it, a switch?

[Piru]

The Leviton, on the other hand, isolates the various host MAC addresses from the cable modem so the cable modem thinks its only talking to a single MAC address (the one belonging to the "switch"). All the packet switching is done "below" any IP addressing. Is this not what makes a switch a switch?

No. Switches pass the mac address along. In fact, switches keep some lookup-table of the 'mac address vs port' correlation, that way the traffic is unicast, it can send the packet to the correct port directly. Multicast ethernet things (such as ARP discovery) are obviously sent to all other ports.

Hub on the other hand just clones the sent packets to all other ports (making them slower than switches).

Higher level things such as NAT require more intelligent and complex hardware: a router.