Networking & wireless: WiFi setup limits me to only using one device.

WiFi setup limits me to only using one device.

I have a wireless router in my home, from which I get net access to my Mac Pro desktop via an Airport card.

However, when I try to use my iBook laptop, logging into my home WiFi knocks the desktop Mac Pro off from internet access. Same happened when I log my iPhone onto my WiFi as well.

Both are set to Dynamic DHCP.

Any advice appreciated. Mac Pro is on OSX 10.4.11, router is D-Link, which is hooked to a cable modem.