Folks, ... why is networking and administering of the same such a trouble sometimes? I have two computers in the apartment and one ADSL USB modem. Local network connection works on both ways, whether it is trough DHCP or manually configured. I have an option to let DHCP to manage the shared wan protocol, but it works until I don't reboot the host computer. The other PC is going trough twisted cable. Is it normal to assign IP addresses every time I turn the host PC on? Something tells me - no. Any help is appreciated.
I think that your ISP is making a trouble, as some of them just don't allow multiple connections to one modem/router. Modem in your case. I had several situations such as yours is, and rules are rules. To make your self sure about that, install fresh copies of operating system, on both machines and re-establish everything again. Than you 'll know for sure do you need to change your ISP or not.