we're gonna be talking about
troubleshooting your cable modem did you
know your cable modem has a hidden user
interface you know all the data and that
it hidden interface and help make your
home internet more reliable and even
faster I'm going to walk you through
logging into your cable modem interface
and detail what all that gibberish means
but first I'm Brady volt
founder of the volt firm and nimble this
I have nearly 30 years experience in the
broadband in cable modem industry I'm
here to provide education and not
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content back to the show there are many
reasons you could be having internet
issues with your cable modem many times
you may find the easiest thing to do is
a simple reboot of your cable modem
unplugging power supply on the modem and
plugging it back in again after a few
minutes the modem will come back online
and the problems will be fixed however
you really don't know the root cause I'm
going to show you how to log into your
cable modems diagnostic page but more
importantly I'll go over the data on
those pages let's get started nearly
every brand of cable modem you will find
you can log into the cable modems
diagnostic pages using the IP address of
192.168.1 hundred dot one or 192.168.0.1
the default username and password will
vary promote them to modem but it's
generally easy to find via a Google
search just search on your modem make
and model along with cable modem login
and you'll see a number of hits in most
cases the username is admin and the
password is password there are some
variations in my example I will be using
an heiress SB 60 180 three dots is 3.0
modem I log into it I'll be connecting
my computer directly to the back of the
Ethernet port on the cable modem I need
to do this because this is a test modem
I have a bunch of
modems laying around that I'll be doing
this with depending on your router or
firewall you may find you can log into
the modem without connecting directly to
the back but if you find you can't do
that then just connect your computer
directly to the back of the modem to the
Ethernet port you just do that for the
purposes of logging in I always
recommend not connecting your computer
directly to the back of the cable modem
because there's no firewall in many
cases for that so we are connected up
here we're going to go ahead and login
and show you what that page looks like
here we are at the login page and at the
top you can see it's one 92168 dot 100.1
at the very top on the status of the
modem we find number of valuable pieces
of information as far as follows at the
very top we can see that the modem has
acquired downstream channel lock this
simply means that the modem has found a
valid DOCSIS channel and was able to
obtain a signal lock which is the first
stage of cable modem registration
process next we see the connectivity
state which is operational meaning that
the modem is online and registered with
the cmts things are looking good so far
the bhoot state indicates that the modem
software is booted without any issue and
next we see the configuration file shows
ok the configuration file is a very
critical step during the modem
registration process the cable modem
downloads the configuration file from
the TFTP server using the trivial File
Transfer Protocol from the cable
operators head end this file consists of
a plethora of details the cable modem
needs to know including the maximum
download and upload speed from your
modem
security is showing disabled on my modem
what security means on the cable modem
is baseline privacy interface
specification or BPI plus this security
encrypts data between the cable modem
and the cmts
this encryption is mostly provided to
prevent theft of service by subscribers
when enabled is very difficult to
eavesdrop on another users modem even
when BPI Plus is disabled as in the case
of my modem because data is being
transferred is modulated on an RF signal
to do so meaning to try to eavesdrop on
this data one would need a very
expensive DOCSIS protocol analyzer and
they would also need to directly connect
through the coax cable so while not
impossible it is by no means trivial to
eavesdrop on someone's communications
between the cable modem and the cmts
next up we see dioxis network enabled
shows allowed what this means is I'm
allowed to communicate to the internet
over my cable modem if this is not
allowed well that might mean that I
didn't pay my cable bill or maybe I
connected a able modem up to the network
but didn't actually subscribe to the
service so if for some reason not
allowed as indicated here or an O as
indicated here that would be indicated
that your cable modems online but you
can't actually communicate or connect to
the service
now the next two sections on here show
your downstream and upstream channels if
you are having any type of internet
performance issues at all this is the
place that you're going to want to look
so let's look at each section in detail
so first let's look at the downstream
bonded channels on the downstream we can
see that the modem is bonded to or using
eight downstream channels on your modem
you may see that you're using a little
more or less downstream channels that's
completely dependent upon how your ebo
operator has configured your cmts you
may have a modem that can do 32
downstream channel bonding but if your
cable operator only has their cmts
configured for 8 downstream channels
then you may only see 8 downstream
channels as what we're seeing right here
my modem for example and do I think this
modem can do 16 channel downstream
bonding but my cmts is only configured
for 8 downstream channels so that's what
I'm going to see when I log into my
screen
each channel is locked which is what I
want to see here if one channel was not
locked then I would be in what's called
partial mode in the downstream but I
have a full lock on each downstream my
modulation is doing 256 qualm in all
versions of DOCSIS there are two types
of downstream modulations for each
single channel carrier one type is 64
qualm which will support roughly 27
megabits per second per channel and the
other type of modulation is 256 qualm
which will support 37 megabits per
second per channel since my modem is
locked to a channels at 256 qualm my
modem could theoretically have a total
downstream speed of 8 times 37 megabits
per second which is a total of 296
megabits per second my actual total
downstream speed will be limited by how
much I'm paying my cable operator for
don't worry about the channel ID that's
something that the cable modem uses
internally track of each channel each
channel has its own frequency that
basically tells us what frequency the
channel is using to communicate with in
broadband we use a cool term called
frequency division multiplexing or FDM
this just means we use many RF
frequencies and stack them side by side
so that the channels don't conflict with
each other each channel also has its own
receive power and this is just the
amount of RF signal entering to the back
of the cable modem the ideal receive
power you want to see coming in the
cable modem should be between -10 to +10
DB mV once your modems channels start to
exceed these values either too low in
power or too high in power and the
performance of your cable modem could
become degraded
next we see SN R which stands for
signal-to-noise ratio and I I will
digress for just a moment here SNR is a
baseband measurement typically used for
measuring the quality of audio and video
signals before they're up converted for
transmission in the cable industry we
have a history of incorrectly using SNR
to label the digital signal quality
measurements of signals the correct
terminology for this measurement is
modulation error ratio or M er as a user
you'll see SNR and m e are used
interchangeably in the cable in cable
modems in C MTS's in test equipment
literature and more if you're a stickler
for being technically correct then
please know that M er is the correct
term as these measurements are analyzing
the quality of demodulated digital
signals not baseband analog signals I
digress no more the minimum m ER or snr
on my modem that we need for an error
free reception of 256 qualm signals is
31 DB as you can see with my modem we
are getting far higher than 31 DB won't
more than 10 DB higher than the minimum
so one would believe that everything
should be perfectly fine with my modem
next up is corrected and uncorrected
codeword errors corrected and
uncorrected codeword errors are likely
the most important indicator of your
modems performance first what are they
to really understand codeword errors you
really need to Google reed-solomon error
correction which is used for all DOCSIS
versions prior to DOCSIS 3.1 you want a
google LDPC low-density parity-check
error correction when you're looking at
DOCSIS 3.1 OFDM and OFDM a signals if
you happen to see those running on your
cable modems name but at a high level
corrected packet occurs when your cable
modem receives some data the data has
errors but error correction is able to
repair the errors in the data so your
computer never notice the error at all
it's pretty much like the error didn't
exist and uncorrect and on the other
hand occurs when the modem receives a
packet of data with some errors but the
error correction was unable to repair
the errors so the modem just discards
that data when the modem discards the
data your computer either has to request
that the data be retransmitted in the
case of tcp/ip or if you're using a
real-time service like voice and video
you may notice some lost voice or video
traffic
so the next section now is dealing with
data that's being transmitted by your
cable modem to the cmts through the
cable operator and really to the rest of
the Internet these are channels that
your modem is using to transmit data on
the upstream similar to the downstream
you can have anywhere from 1 to 8
upstream channels that your modem can
transmit data on depending on how your
cable operator has configured their cmts
in this example we see there are 4
upstream channels each channel is locked
so they are in an operational State the
upstream is using a TDM a or
transmitting data discussion on the
channel type is out of scope for this
topic but suffice it to say that the
channel type will not have any impact on
your modem unless you're looking to
purchase a modem or your own and I'll
cover my recommendations on buying your
own modem in a future video again you
can ignore the channel ID is this is
used internally by your modem to keep
track of the channels the symbol rate
indicates the bandwidth of the upstream
channel where to five six zero killa
symbols per second results in an
upstream channel width of 3.2 megahertz
and five one two zero killa symbols per
second results in an upstream channel
width of 6.4 megahertz each channel has
its own upstream frequency betta
transmits on in the upstream the modems
use frequency division multiple access
or FDMA that's a little bit different in
FDM in the downstream and that just
means that modems use frequency stacking
but each modem must wait their own turn
to transmit data in the upstream the
cmts allocates time slots to the modems
so that your modem does not transmit at
the same time on the same frequency as
your neighbors cable modem
and finally we see the transmitted power
or each able modem the ideal transmit
power that we want to see for each
channel is between 40 to 50 DBM V this
is really important if the transmit
power is too low for your cable modem
and your modems transmitted signal can
get lost in the noise floor if the
transmit power is too high say your
cable modem is transmitting at 52 DBM V
or higher then your modem may run out of
transmit power and its signal will not
be able to reach the CMT s it is usually
very difficult for a subscriber or a
homeowner to do anything about low
transmit power but if you're not
experiencing any issues with low
transmit power and your modem don't
worry about it
not a problem high transmit power will
many times be caused by bad in-home Bo
acts or connectors or the coax and
connectors just outside of your house
this is something you can tackle and
make a big difference in my video on t3
timeouts I briefly covered this topic
and I'll also be doing a much deeper
dive on in home wiring in a future video
now we're going to look at the event log
let's go back to the top and you'll
generally see an event log tab click on
that event log tab and here we can see a
lot of concerning things and I this is
also where I've talked about t3 and t4
timeouts this is where you'll see those
type of events in my event log we see a
lot of DHCP renewal warnings a lot of
TOD or time of day warnings these are
completely normal and can be ignored in
fact there'll always be a lot of events
in your cable modem event logs which can
look quite scary but as long as you're
not experiencing any type of issues
these notifications are completely
normal and should just be ignored don't
don't get worried about things that you
see in event logs like MDD messages lost
synched messages a lot of the messages
that you're seeing in my event log if
you're not having problems with your
service if you're not experiencing
issues and you see things in your event
log and they say error error warning
notice don't worry about them only be
concerned about things in your Event log
when you're actually experiencing
problems with your cable modem so what
type of things do you not want to see in
your cable modem let's look at an
example we see an example here of a
cable modem that is not locked on two of
its upstream it's locked on upstream
zero
sixty-four qualms 35.8 megahertz
it's not locked on channel 2 and it's
not locked on channel 3 this was sent to
me by a colleague who first noticed they
had slowed data speeds they looked at
their modem and noticed that the
upstream LED on the modem was orange
you'll notice that there's multiple
lights on your LED there's a top light
it's gonna tell you that the first of
all the modem is on the second light is
normally your downstream light the third
light is normally your upstream light
and the very bottom light is normally
the registered light all is disconnected
and communicating so this was the light
that was orange that gave the user the
indication that there is actually a
problem upon logging into the modems
diagnostic page they found what they see
below who channels were offline one
channel was online this is called
partial mode partial mode occurs when a
modem is you only using some of its
available upstream or downstream
channels in this case the modem could be
transmitting on three upstream channels
but two of the upstream channels have
become unlocked there are many reasons
this can occur but most are due to some
type of impairment in this scenario the
issue result was resolved by simply
unplugging the cable modem for a few
seconds and plugging it back in once the
modem came back online all three up
streams were back online and locked the
orange LED was again green and easy
fixed by the homeowner without calling
the operator so one more cool feature on
most DOCSIS 3.0 and higher cable modems
there's a built-in spectrum analyzer
access the spectrum analyzer a pen port
8080 to the end of the IP address so
let's see how this works
go back in we're going to go up here to
our IP address
one 92168 100.1 will put a colon 8080
and we'll hit enter and we see this
spectrum analyzer come up
we go over on the right hand side and we
click run right there we are seeing all
the RF signals coming in there's a lot
of cool features on the right hand side
I'm gonna leave it up to the user to go
ahead and play with most of these for
those of you who like to play with cool
tools this one's for you you can see all
the RF signals coming in to your modem
there are many features on the spectrum
analyzer but I'll let it up to you to
play with these settings and see what
you can find spectrum analyzer is also
what cable haunt was built on which I
covered in another video which I'll put
in the link below
and also a tag and above so wrapping it
up this was a basic overview of the
cable modem internal diagnostic screen
you will find some cable modems contain
more or less detail also you may find
some cable modems and some cable
operators may not give you any access at
all to these diagnostic screens
unfortunately subscribers will take data
and abuse cable operators with it by
this I mean they will constantly harass
their cable operators anytime a single
parameter is how to spec please do not
do this or you will ruin it for everyone
I'm providing you with this information
so that you as a subscriber and help
diagnose and fix issues within your own
home cable operators and their
technicians work very hard to keep
networks up and running I personally
know it can be frustrating to have your
internet service down or impaired
however many times the issues do start
within your own homes internal wiring
and things we do without even realizing
it like moving a cable modem around or
changing how the coax runs from point A
to point B in our houses the cable modem
Diagnostics screen gives us has end
users the ability to self-help I'll be
doing more videos on just that how to
fix issues in our homes until then
thanks for watching