Re: Linksys Wireless Router and Dropped Cable Modem Connections

On Fri, 6 Aug 2010 08:38:22 -0700 (PDT), in
<22405c45-7dc2-49c7-9bd7-(E-Mail Removed)>,
three-eight-hotel <(E-Mail Removed)> wrote:

>I have a problem that is driving me nuts! I have a Motorola SURFboard
>(SB5120) cable modem, and am using Comcast cable services. I also
>have a Linksys Wireless Router (WRT54G).

Which flavor (version)? Which firmware?

>Initially, the two worked well together, with my PC wired to the
>router, and an occaisional laptop connection. Since then, we have
>started to add wireless devices to our list of assets (iPhone,
>iTouches, iPad, Wii and a wireless printer). Although it seemed like
>it was around the time that I enabled the Wii to take advantage of the
>network, it appears that I have periodic issues, although less
>frequently. (We are using Wii to stream NetFlix movies)
>
>The problem is that the cable modem seems to get knocked off-line, a
>lot! Sometimes, several times an hour!

How do you know the problem is the cable modem?
Do the lights show it as down?
Did you have Comcast check the status of the cable modem?

>I work from home, and end up plugging the cable modem directly into my
>PC, so I can get through the day, without getting dropped, but it
>takes the wireless router out of play, hence the wife and kids can't
>enjoy their wireless devices!
>
>This is killing me! Is it the wireless router? Is it the cable
>modem? Is it a combination of both??? I'm willing to purchase new
>hardware, as long as I know what/who the culprit is.

The usual problem is the crappy firmware in the WRT54G, not the cable
modem. Upgrade to the latest firmware version. If that does not help,
switch to DD-WRT (build 13525) if you have a compatible model.

--
John FAQ for Wireless Internet: <http://wireless.navas.us>
FAQ for Wi-Fi: <http://wireless.navas.us/wiki/Wi-Fi>
Wi-Fi How To: <http://wireless.navas.us/wiki/Wi-Fi_HowTo>
Fixes to Wi-Fi Problems: <http://wireless.navas.us/wiki/Wi-Fi_Fixes>

On Fri, 6 Aug 2010 09:39:15 -0700 (PDT), three-eight-hotel
<(E-Mail Removed)> wrote:

>> Which flavor (version)? Which firmware?
>SURFBoard:
> Software Version: SB5120-2.19.0.16-SCM00-NOSH
> Hardware Version: 4
> MIB Version: II
> GUI Version: 1.0
> VxWorks Version: 5.4
>
>> How do you know the problem is thecablemodem?
>I don't know the modem is the problem? Assuming, based on ability to
>stay on line with the router out of the picture (pc plugged in to
>modem directly)
>
>> Do the lights show it as down?
>Light do go off, when it goes off-line. Seems to go through a series
>of resets???

You don't mention which lights go off, which would be very helpful to
know.

You can also check your cable's signal levels by pointing your browser
at http://192.168.100.1/signal.html

The three key areas to note are
- Downstream Power, which should be between +-15dBmV, with +-10dBmV
being desirable,
- Downstream SNR, which should be in the mid to high 30's, with
higher being better,
- Upstream Power, which will probably be over 45dBmV but should be
well below about 55dBmV.


Having said this, I agree that the primary issue seems to be the
router, not the modem, going by what you've provided so far.