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doofusmaximus

# Posted: 24 Oct 2009 15:29


Here's one for you that 2 hours with Comcast tech support doesnt resolve. I have a comcast cable modem plugged in to a linksys wireless router. ALL wireless devices work just fine, but two weeks ago my PC's connection (direct via router) stopped working (limited/no connectivity).

NOW when I plug ANYTHING (4 laptops now and desktop) DIRECTLY in to the modem, I get an IP address 169.xx.xx.xx and no love, but when I plug the modem in to the router, BINGO wireless works fine (192.xxx ip addresses) and desktop plugged in to router cannot even sniff the network...

Modem - Scientific Atlanta
fixes tried: comcast service reset of modem (4x)
countless re-boots of modem, desktop, router, etc...
Shnerdly
Moderator
 # Posted: 24 Oct 2009 21:19 - Edited by: Shnerdly


Unfortunatly, many service desk techs don't realize that whenever you change the first device connected to the cable modem you must restart the modem by unplugging the power and plugging it back in. This is not a suggested method, it is required or the modem will assume the device connected to it is still the original device but it won't be able to communicate with it because the MAC address is wrong. So with each of the 4 laptops and the desktop you would need to restart the modem and then start the computer to gain access to the Comcast network.

As far as the router working wirelessly but not with wired connections, it could be a bad router, a bad port on the router or corrupt firmware in the router. I would suggest doing a reset of the router by pressing and holding the reset button for 20 seconds while the router is powered on and see if that helps. If that does not help, try upgrading the firmware of the router.

Here is a more detailed description of a home network.
doofusmaximus

# Posted: 24 Oct 2009 21:49


Good advice, but Im afraid I am still stuck. I plugged desktop directly in to modem, rebooted modem, rebooted computer, still getting 169.xx IP address on IPconfig. Ive also tried:
ipconfig/release + renew
ipconfig/flushdns
ipconfig/registerdns

ALL to no avail. Anything else? Again, Im just trying to re-establish direct to modem connectivity, right now Im connected wirelessly via the router and all is well.
Shnerdly
Moderator
 # Posted: 25 Oct 2009 17:59


You said you "rebooted" the modem and "rebooted" the computer. That doesn't satisfy me that you did things in the correct order. Reboot would imply that you made the connections with the devices powered on.

Because it is working wirelessly, we know the modem works. To get the modem to recognize the new device connected to it, namely the laptop, you MUST unplug the power to the modem (it's best to leave it off for a few minutes). While the modem is unplugged, make the ethernet connection to the laptop with the laptop turned off. Now start ONLY the modem and allow it to boot (about 30 to 45 seconds). Now start the computer. It should now get your new external IP address transfered to the computer and be online.
Anonymous

# Posted: 26 Oct 2009 21:56


ok, took my 'puter to the office, plugged in to LAN, WILL NOT RECOGNIZE, still get limited access, I have tried:
Updating driver for the NIC (downloaded on my laptop, xferred via jump)
resetting winsock
resetting something else
ipconfig/release
ipconfig/renew
registerdns
flushdns
Had my IT guy set the configure the IP address manually

annnnnd NADA....great googly moogly
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