Problems with Router/Firewall and cable modem

From: ParrotRob (
Date: 07/23/03

  • Next message: Bill Unruh: "Re: Am I more vulnerable using broadband?"
    Date: Wed, 23 Jul 2003 14:41:39 GMT

    OK, I've tried asking this in other places and no one seems to have an
    answer. Maybe some of you folks here might.

    I've been using Adelphia's "PowerLink" cable modem service for about three
    years now here at home. For obvious reasons, I installed a LinkSys router
    in between my computer(s) and the cable modem. Since that time I have
    replaced the LinkSys router with a DLink combo 4-port router and 802.11(g)
    wireless access point, and also installed a Netscreen 5XP firewall between
    the DLink and the modem. The Netscreen is primarily for work purposes since
    I work from home and it allows me to set up VPN connections between my home
    network and the office. I'm also using the Netscreen as my DHCP server for
    the inside private network. So we have:

    Cable Modem ----> Netscreen ----> Router/AP ----> bunch of PC's

    No problem, right? Right - up until about a month ago when I lost my
    internet connection and couldn't get it back. In the process of
    troubleshooting, I eventually got down to plugging a single PC directly into
    the cable modem - at which point it worked JUST FINE. To this day, that is
    still the case.

    Unfortunately, since that is the only configuration that Adelphia officially
    "supports", they refuse to acknowledge that there is a problem. However,
    the problem is that ANY DEVICE WHATSOEVER that is NOT a PC, refuses to get
    an address from my ISP. That goes for the Netscreen, the DLink's WAN
    interface, and the old LinkSys's WAN interface (yes I drug it back out to
    test it). Further investigation of the Netscreen, from the command prompt,
    finds that when I put the untrusted interface in DHCP mode, the firewall is
    actually able to SEE a DHCP server, and even the address/subnet/gateway that
    is offered by the DHCP server - but for some reason the interface will not
    take that.

    Can any of you think of a reason why all of these network devices have great
    difficulty connecting to the ISP via DHCP while a simple single computer
    does not?

    For the record, a close neighbor (on a different router, undoubtedly) has
    the same cable modem service, and all of this gear works JUST FINE at his
    place - yet the cable company refuses to acknowledge that the problem just
    MIGHT be on their end.

  • Next message: Bill Unruh: "Re: Am I more vulnerable using broadband?"

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