[Wlug] Test needed on declared-ill Modem. Who has a lab?

John Stoffel john at stoffel.org
Thu Sep 27 14:28:19 EDT 2012

E> I don't know how much of the recent comments are directed to me, or
E> which were responding to Richard.

I was just chiming in with a general comment on Charter's tech
support, and how I was pleasently surprised how easy it was to get my
NAT router changed without having to talk to a tech at all.  

E> This here:

>> Make sure that you update the MAC address with charter, and that
>> they actually update it. I've had a few problems where they
>> haven't even though they said they did.

E> Yes! That happened to me, and the modem had to be re-registered two or
E> three times. It depends on the tech you talk to. My modem was incorrectly
E> or incompletely registered here by the install tach on the day the service
E> was hooked up. The internet generally worked as it should anyway, but
E> during times when there were connectivity problems here (see below), in
E> phone calls to tech support, every once in a while the tech would tell me
E> "I" had the wrong MAC address, that I was running an unauthorized modem,
E> etc.. Then I would have to explain why that seemed to be, and they would
E> try again to get that corrected.

E> My history here:

E> Charter here needs a DOCSYS3-compliant modem. I was running a Motorola
E> SB6120, which worked fine for 27 months. This has several nice diagnostic
E> pages, accessed at, including logs which give details of any
E> exceptions and error messages.

E> Connectivity problems in summer of 2010 were caused by new lines (coax)
E> from the pole to the box. I was able to prove to the provider that the
E> intermittant problems were not in my setup, but outside. There were several
E> issues, which they gradually seemed to fix. One had to do with connectivity
E> interruptions on the days following a big rainstorm. The connectors in the
E> new lines (at the pole) had not been weatherproofed, which they did.  Line
E> techs eventually checked and improved the weatherproofing throughout the
E> whole neighborhood.

E> Note that I have no other services (such as TV) which run on the incoming
E> line. Also note: I have no extra connectors in the coax running between the
E> box and my modem.

E> The sick modem I experienced here a few weeks ago may have simply been due
E> to a failing power supply (wall wart) running the modem.  Somehow that had
E> never occurred to me. I could have tested that by replacing it with an
E> equivalent new power supply.

E> Meanwhile 2 Charter techs had diagnosed my modem as 'dying', shook their
E> heads when they learned it was 2+ years old, replaced it with one of
E> theirs, and left. This is a Cisco, which sounded reasonable to me. But
E> there is only one page available to customers, at and this
E> only shows that the modem is connected, a few power levels, SNR, how many
E> channels are running. Further diagnostic pages can be accessed through a
E> password, but the usual logins and passwords don't work.

E> My ultimate solution is to get another modem which I will own and have
E> provisioned when I set it up. The one I'm planning to get is the Motorola
E> SB 6121, their replacement for the 6120, which they no longer manufacture.

E> A further note on the SB6120, in case anyone gets one on ebay or whatever:
E> These are very sensitive to incoming power levels. If the signal is too
E> "hot", such as 15 dBmV, they start throwing errors. These power levels seem
E> to vary according to temperature and humidity. Once I installed a 3db
E> attenuator pad between the incoming coax and my modem,  the power levels
E> the modem experienced came down to 10 or 12 dBmV, which allowed the modem
E> to operate without interruption for many months at a time.

E> I haven't heard if the SB6121 has the same sensitivity to hot power levels
E> or not. I'm still reading reviews and forum posts about this unit. I can
E> report on it once I get one in here and running. It will be nice to be able
E> to see the diagnostics pages and service logs again.

E> Liz

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