Hookup to Cable Modem

Discussion in 'Network Routers' started by Michael Dobony, Dec 25, 2010.

  1. I tried to hook up an old linksys BEFW11S4 router to a cable modem and had
    extreme difficulty. I ended up getting the wired network to work by hooking
    the modem to the LAN instead of the internet port. However, it would not
    connect the wireless to the internet. That same router worked flawlessly on
    another system for both wired and wireless connections by hooking up to the
    internet port. I thought of getting a router/modem combo, but the phone
    system runs through the modem also. My next plan is to try a Linksys
    WRT54X2. There are many more settings on this router. Any ideas on how to
    get both wired and wireless connections working on a cable modem?
    Michael Dobony, Dec 25, 2010
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  2. Michael Dobony

    Char Jackson Guest

    Like what, specifically?
    All you accomplished was to completely bypass the router, essentially
    turning it into a switch.
    Can wireless systems connect to the router and communicate with wired
    systems connected to that same router? In other words, check the local
    networking first, before thinking about Internet access. You may have
    to temporarily disable wireless security to verify full wireless
    functionality, but I wouldn't run without better-than-WEP (and
    preferably WPA2 AES) for very long.
    Do a full factory reset on the router. It sounds like someone screwed
    up the settings, err, I mean, customized the settings beyond
    functional limits. The default settings should work in most cases.

    As stated above, verify local networking first, then log into the
    router and make sure it has acquired an IP address and related config
    info from the ISP.
    Char Jackson, Dec 26, 2010
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  3. I could not communicate past the router until I moved the router to modem
    cable from the Internet port to the LAN port. This got the wired connection
    working, but not the wireless. The wireless could see the local network
    except for the modem (it could see the router and the wired connection to
    the desktop.
    The WEB router only has WEP.

    I started there and could not get past the router to the modem no matter
    what I did.
    That is what I did with the local network. I could not get past the router
    to the cable modem and the internet until I moved the router to modem line
    from the Internet port to the LAN port. Wired connection went past the
    router to the modem and internet, but wireless would not, no security on
    the wireless.
    Michael Dobony, Dec 26, 2010
  4. Michael Dobony

    Char Jackson Guest

    Yes, but connecting both the computer and the modem to a couple of the
    router's LAN ports was effectively the same as connecting the computer
    directly to the modem, so I wouldn't say that got it working.

    Did you remember to reboot the modem after making the initial cabling
    change? Usually, the modem's config only allows it to talk to the
    first device it sees after a reboot/power-up, so if that was your
    wired PC it won't talk to your router until you reboot the modem with
    the router correctly connected, which is to say that the router's WAN
    port needs to be connected to the modem.

    During the time that you had the modem connected to a LAN port on the
    router, it makes sense that the wireless computer couldn't see the
    Internet. As stated above, since your modem can only talk to a single
    device and you let that device be your wired PC, the wireless computer
    had nowhere to go.

    Bummer. If you live near other people, be prepared to share your
    bandwidth and any open file shares. WEP security can be bypassed in
    under a minute now.

    I'm guessing you forgot to reboot the modem. Correct the cabling, then
    reboot the modem, the router, and possibly the PC's, in that order. As
    the modem restarts, it will find the router. In turn, the router will
    request an IP address from your ISP. You can log into the router to
    see if that is successful. Lastly, your wired and wireless PC's will
    request an IP address from your router if you're using DHCP, and away
    you go.
    Char Jackson, Dec 26, 2010
  5. Yes, I rebooted.
    Already changed that one out for a different application
    That is what I did. Hopefully the other router will behave properly. Will
    get access to it again Monday morning.
    Michael Dobony, Dec 26, 2010
  6. Monday was a messed up day and ended up going there Thursday. I started
    with a factory reset on the router and restart on the modem (Arris TM502G
    cable modem). I could not pass through the router to the modem. I copied
    the computer settings (pre-router install) to the internet setting on the
    Linksys WRT54GX2 router for a manual setup and still not communicating. I
    tried all kinds of settings, but nothing would work. I experimented with
    NAT, DNS, DHCP, etc., on the router and the computer, but could not get it
    to pass through to the modem or internet. That same router works great in 2
    other applications not involving a cable modem, but rather DSL. I am
    totally unable to access any functions on the modem. There do not seem to
    be any settings on it.
    Michael Dobony, Dec 31, 2010
  7. Michael Dobony

    Char Jackson Guest

    When I see things like "tried all kinds of settings" and "experimented
    with", the first thing I think of is that it's time for another
    factory reset. Be sure you aren't doing a simple device reset. Pushing
    the reset button for up to about 10 seconds simply reboots the router
    and doesn't reset the settings. With the router turned on, you should
    press and hold the reset button for a full 30 seconds. You'll know it
    did a full reset when you notice that the default user/pass is now
    required to login, rather than the user/pass that you had set before.

    Here's how I would proceed, if it were me:
    1. Full 30-second factory reset of the modem.
    2. Connect an Ethernet cable from the modem to the router's WAN port.
    3. Reboot the modem so it learns the MAC address of the router.
    4. Connect a computer (via Ethernet) to one of the router's LAN ports.
    5. Log into the router and check the Status pages. Verify that the
    router has requested and received a routable IP address from your ISP,
    as well as one or more valid DNS addresses. Go to the router's Admin
    page and use Ping or Traceroute to check connectivity FROM THE ROUTER
    to an Internet IP address. ( and are two addresses that
    are easy to remember.) If the router can reach those addresses, then
    the path from the router to the Internet is good. At that point, if
    you still can't pass traffic from your PC to the Internet, it's the
    router itself that's blocking the traffic. Since you would have done a
    full 30-second factory reset prior to this, things like access filters
    will be disabled, so I would suspect a bad router.

    Be ready to try a second Ethernet cable for any segment of the network
    path that isn't working. Cables can and do go bad from flexing and
    other handling.
    Like virtually all cable modems, its configuration duties belong to
    the ISP, so all you can do as a customer is view a few things like
    signal levels, log files, MAC addresses, etc. It looks like the
    modem's IP address is
    Char Jackson, Dec 31, 2010
  8. I did SEVERAL of these full resets. Each time the settings went back to

    Nope, no access through ping or trace. Tried that. Both routers are working
    in other environments with no adjustments from factory other than custom
    names and password protection on the wireless.
    Same cable as used successfully in other environments.
    Yes, correct.
    Michael Dobony, Jan 4, 2011
  9. Michael Dobony

    Char Jackson Guest

    What about the most important part of those steps, verifying that the
    router successfully acquired a routable IP from your ISP?

    By the way, does your ISP require you to register your computer's MAC
    address with them? If so, you'll need to clone that MAC in the router
    or you won't get Internet access.
    And? Were you able to access the status pages in the modem? If so,
    you're getting through the router.
    Char Jackson, Jan 4, 2011
  10. No, it is not. That is the problem!
    That is one setting I did not try.
    No, I could not access the modem through the router.
    Michael Dobony, Jan 4, 2011
  11. Michael Dobony

    Char Jackson Guest

    I agree, that is the problem. Up to this point, I have assumed that
    your ISP uses DHCP to assign you a routable IP address, but it's
    possible that they use something else, such as PPPOE. Find out, either
    by searching their web site or by calling them, whatever, because
    until you can get them to assign you a routable IP, you're not going
    Char Jackson, Jan 5, 2011
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