1. TechSpot is dedicated to computer enthusiasts and power users. Ask a question and give support. Join the community here.
    TechSpot is dedicated to computer enthusiasts and power users.
    Ask a question and give support.
    Join the community here, it only takes a minute.
    Dismiss Notice

Comcast+Motorola Cable Modem+ Any Router=Problems

By gotwood
Aug 25, 2006
  1. I'm having problems getting my home network to work smoothly. I believe it is in the communication between router and cable modem. I think these problems all started when Comcast implemented Bridging in the modem(im not positive). Not sure if this is IP address related , MAC address related or another problem. What I do know is that.....

    A. Sometimes even the wired connection to router goes out and can require some or all of following. Restart Modem, Restart Router. Restart Computer and/or "repairing" network connection.
    B. Wireless connection..Wireless Networks can be "seen", but cannot get an IP Address when "repairing" or connecting.
    Any type of Description to how routers/computer/modem interact would also be appreciated.
  2. jobeard

    jobeard TS Ambassador Posts: 10,432   +801

    B is a consequence of A, so make A work reliably first and then address the
    stability of the wireless thereafter.

    Lots of issue here, including specific brand names and even model numbers.
    At the top of your list of suspects is Comcast; there's a lot of flap re their support.

    An ISP can configure their end to be very parochial to force specific
    operations, such as allowing access to only KNOWN users. When installed,
    they can record (assuming no router is yet installed) the MAC of the system
    that is connected. {hint: this is a good security measure for even your LAN}
    This is also where your WAN (ie public) IP-Address gets determined, either
    statically per your service contract or dynamically via DHCP on the ISP site.

    If your ONLY system is directly connected to the modem, it will receive these settings.

    Modems are transducer devices, ie they change one technology into another,
    just like a radio changes a/c or d/c power into rf and then into audio.
    Most of them have little functionality beyond that.

    Routers are great devices and have many features. The most important is
    NAT to allow multiple LAN devices to use the WAN-ISP connection. This also
    acts as a primary firewall due the fact the the LAN side address can not be
    (directly) attacked from the WAN side :)

    If you have a router, the side connected to the modem will be configured to the ISP
    settings for your connection. If the ISP records the MAC address, you will
    need to force the router to masquerade as that specific MAC address
    as no connect will suceed w/o it (in this case).

    Last comment: The ISP will periodically force a RELEASE / RENEW cycle on
    your connection. This is where most cheap routers have problems like you report. ALWAYS try to keep the firmware updated.
    Search this board (or google) for your brand name router for histories of issues
    encountered; eg: Linksys WRT54* seems to be frought with issues.
  3. gotwood

    gotwood TS Rookie Topic Starter

    Well, In regards to routers. I had a netgear 80211.g(cant remember the model number) which worked very well for over a year. Then the problems started(I think when comcast implemented router bridging). Since then we tried two other netgears, a D-link and A linksys.
    I would say netgear=least problems linksys=most.
    I am considering Going to the motorola gateway, but It only has one ethernet port. I am worried I will run into the same problem using a router after that for the hardwires.
Topic Status:
Not open for further replies.

Similar Topics

Add New Comment

You need to be a member to leave a comment. Join thousands of tech enthusiasts and participate.
TechSpot Account You may also...