Here is my setup.. The BSNL modem's LAN 1 is connected to the iMac. It all works fine. But as soon as I switch on any of the windows PC on the both sides, the modem gets crazy and the whole line gets unstable. Like the internet starts going on and off continuously. I dont understand, what is the reason. Is windows system emitting some radio signal or seducing the modem to go crazy ? Dont know, what is it.. Anyone ?