[stomachmonkey]

You have too many devices on your network that left in their default settings will compete for control. I'm not surprised it does not function properly and would be shocked if it actually did.

You're Cable modem is most likely a router, if it is, all you need is/are hub/s to add devices to your network.

If your cable modem does not act as a router then you add 1 router and hubs behind it.

Every device on a network requires it's own unique IP address.

The modem supplies at least 1 IP address to your network, if it is a router as well it can supply as many as you'll ever need via DHCP.

By default consumer routers are configured to act as DHCP servers. You should only have one DHCP server, you have at least 2 if not 3.

You are way overcomplicating this.