Cannot use multiple PCs with cable modem

Hi all.

So I'm totally stumped, and in need of help.

We have just had a new internet connection set up at our new flat. Its cable from telstraclear NZ. They provided us with a modem (motorola sb5101i) with a single ethernet port.

When the technician came to set up the nets, he made sure it was working by hooking up one of our laptops, entering the manual IP info which we must use (i assume the modem isn't DHCP compatible), and the laptop connected fine and now has a working internet connection.
However, we can't get any of our other systems to work. We all have PCs (4 of us), all running windows 7 and using on board networking via ethernet. at first we tried connecting a switch so we could all hook up at once. However none of the other system could connect to the network, so we tried individually connecting up all of these systems. Still though, we cannot get a connection (either using the provided IP info, or asking to to auto fetch via dhcp).

When one of the PCs is connected via ethernet, we can sometimes connect to the network, though sometimes we get an error, usually to do with an IP conflict or problem connecting to the DNS server. In all instances though, none of the other systems get an active internet connection, and only rarely even connect to the local area network.

After over an hour on the phone to the telstra tech support, the only thing i have ascertained is that we should be able to hook these systems up, either via the switch or directly to the modem. and get a connection. there is a problem somewhere, possibly with the modem itself. they have escalated our problem but we still haven't heard back.

any suggestions or info would be great, since all 4 of us are tech geeks, and we are all stumped. We have ordered a new router, in the hopes it will resolve some of our issues, but we are pretty sure its with the modem and so unlikely to be fixed so easily.

so yeah, anything you can offer would be great.
thanks guys.
4 answers Last reply
More about cannot multiple cable modem
  1. Quote:
    When the connection works, you just use Internet Connection Sharing, ICS. make sure this service is enabled

    We've tried this, local network is spotty, we aren't even able to share local files, let alone global access.
    When we have more than once system actually connected, we get IP conflicts and the network refuses to go down.

    I've been trolling google, and it sounds as if the modem is only able to assign a single IP, and that a router is needed for multiple IPs. sounds weird, but possibly the right solution. as we already have router coming we can try it.
  2. Your problem is routing. That Motorola device is a modem, connecting other devices through a switch will not work; you need a router to achieve this.
  3. Get a router, the modem is made to only work with one computer attached to it, not weird at all, it's a very common thing that's done by millions of people. Bit suprized you have not heard of this configuration before, and very suprized that the tech support person did not just tell you that soon as you called. If you actually got a support person that knew more than read off the script you would be working already :-)
  4. Not sure you guys entirely understand the problem.

    its not the one system at a time that worries us, its that even if we connect one system up it will not get a connection.

    Anyways, our router arrived today so we have it sorted. Its a shame we had to buy one so soon though. as we should have been able to take it in turns using the internet.

    thanks all for your help.
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