|When you are connecting the modem directly to a switch, and I assume, you really talk about a modem, not a router/modem, how did you authenticate to your ISP?|
Using a router with integrated modem, the router can authenticate to your ISP.
In that case, all internal PCs simply needs to have the routers internal IP address configured as their default gateway and perhabs DNS and all users should have internet connection.
The original poster should always write the last response !!!
Let us know, if the problem is solved !!!