in that it totally opposes the purpose of the router. I can only think that your configuration settings are wrong. Reset the router to it's defaults and set the PCs to obtain IPs and DNS's automatically. You should be able to connect independently on all machines after you shut down and restart the modem/router and PCs, in that order.
I have a NetGear router connected to 3 computers. I have to set firewall off and DMZ on to connect to internet. Whenever I connect, I have to set the IP address of connecting computer to DMZ setting.
This allows me to connect one computer at a time. Also, each time I change the computer, I have to change the connecting IP for the router.
Is there any easy solution to connect different computers, without changing router settings