Re: Help needed with intermittent internet

Important information that I did not see earlier:
When the internet is down, the Netgear [usually but
not always] will not respond to a ping, either from
within or from the outside.

IOW the Netgear modem has an IP address from your house and cable
company AND has a completely different IP address from LAN -
subscriber's computer. Subscriber may ping to 192.168.1.1 to 'see'
the modem. You may use 216.123.456.23 to ping same modem from other
side. As I now understand your statement, ping works from both sides
or fails on both sides - simultaneously. Is that correct?

Again, cable techs only do what they have done previously.
Therefore, did they run a wire directly from that Netgear, out the
window, and directly to their cable? Typically they don't do it
because it was never necessary previously. Therefore it is one of the
first things I do. Part of breaking a problem down into parts and
then testing those separated parts.

Same concept applies in this paragraph. If grounding is not
verified visually, then a new machine in a nearby other building or
distant utility load changing early every morning may create current
loops in this building. Why must all incoming utilities connect to
the same ground? Among different things performed by a ground so that
electrical problems in other buildings do not adversely affect your
signals. And since inspection takes only minutes, it is usually one
of the first things we look at - when technicians are totally
confused.

Why is grounding important. Well grounding for safety is understood
by electricians. But that grounding also does things that
electricians typically need not understand. Electrician is a
technician who is carefully trained into how to respond to code. Ask
an electrician how to lower impedance in a wire? He would not know.
He knows what meets code. But can he explain why that ground would
eliminate radio frequency noise from a neighbors new machine? To know
that, he would have to learn things beyond what is in code books.

Comcast is better than most cable companies. For example, Comcast
trained their installers to make that ground connection. But there
are still bad installations out there that can only be found by visual
inspection. Improper grounding may, for example, cause rare voltage
spikes to saturate an RF amp. Does that make sense to you? Does not
matter. Checking grounds are an automatic first inspection when
strange things are occurring.

My experience is that cable company does not read meter's analog
numbers - the decibel numbers. They simply say an IP address responds
- therefore modem is 100% OK. - a GoNogo test. But in a real world,
something can 1) respond when signal is sufficient, 2) not respond
when signal is way too low, AND 3) respond when signal is too low.
This world is ternary. That third state is only detectable from
signal strength numbers - both incoming and outgoing - and read from
modem. Assume numbers to be read by Comcast are intermittently
insufficient. They must read and be able to tell you what outgoing
and especially what incoming signal strength numbers are at any
moment. Are they reading signal strength? Well when signal strength
is too low, then Comcast would not see it. They would only see
numbers when numbers are sufficient. Just one example of why I
posted:
Again, your problem is classic of intermittents which is
why a provider should provide S/N ratios on your modem
that you can monitor.

If their answer is 'it is good', then you want to know 'how good'.
Any answer without numbers reports nothing useful. No numbers is
symptomatic of Go-Nogo testing such as ping. Ping would not report
the third of three states listed later.

When your signal strength drops periodically (due to noise bursts that
a missing ground would have eliminated, or due to periodic frequency
shifting, or interference from a neighbors TV, etc), then what will a
remotely located cable tech see? Nothing useful because bad numbers
cannot be read remotely when modem has temporarily failed. An
intermittent failure due to a missing ground, an improperly routed
cable wire inside the building, etc.

Moving on, if Netgear completely stops responding to pings on both
sides and restore on both sides, well, then who is sending a master
reset to the modem? Does he know his test sends a master reset? Yes,
techs do try to solve to the best of their abilities. But how many
know (for example) why proper grounding is essential - what it
accomplishes? Many techs know "When this happens, then we do
this." Therefore many techs don't know what a "we do this" actually
does. Or whether a DOSCIS signal can cause a modem to perform a
master reset.

Every tech does the best he can. But how many are actually familiar
with the DOSCIS standard? IOW they do the best they can which is
"when this happens, then we do that". Why? Not relevant to many
techs which is why, for example, a tech might never understand the
long list of reasons why all incoming wires (AC electric, phone,
cable) must be grounded to a common point. Also would not know why
many electricians also do not know all the reasons for a common
ground.

Moving on again. Modem is down on this morning. What happens when
the modem is power cycled - meaning even power plug is completely
disconnected and reconnected. Does that restore the signal? Does
that permit ping to occur from both sides? Does that restore signal
strength? IOW does modem start working - respond to pings from both
sides when a power-on master reset occurs? OK. Does Comcast reset it
from a remote center. Does power-in reset also do same? (again this
assumes only two possible conditions: modem is both side locked out
and both sides functional.)

What from the subscribers (LAN) side could cause problems? Well I
am limiting this to answers that only explain a crashed modem on both
LAN and Comcast sides simultaneously. For example, a mismatch in
twisted wires for an Ethernet cable could cause problems - but
typically not crash the modem.

Electrically, a voltage must be so high to overwhelm galvanic
isolation inside that ethernet port - such as static electric
discharge from a human. Or noise frequency must be sufficiently
high. I am not fully familiar with the Netgear modem (and could not
find that necessary status page that I believe Comcast intentionally
did not provide). Therefore I am not aware of any simple command that
can lock out ports without some complex human interaction.

Only LAN side event I know of that can lock out the entire modem?
Excessive voltage spike. BTW, same could happen on cable side of
modem because cable wire was not properly grounded.

Doing the same test as should have been done on cable side of
modem. All LAN cables, except one, would be disconnected the night
before. Is modem locked up that morning? Or temporary cables are
routed through doors and hallways. When not using orginal LAN cables,
does modem no longer lock?

And finally, what can you do to make this problem worse? Heat modem
with a hairdryer on high? I will be unable to suggest in this
paragraph because the scene is too far away. Heating modem with a
hairdryer demonstrates the tone of that suggestion. I don't really
believe heat will yield anything useful. But is there something
unique in that room that when exaggerated, would make failure more
frequent? More frequent failures are easier to solve.

On May 6, 9:44 pm, "JM" <j...@xxxxxxxxx> wrote:
...
I'm no expert on internet/WAN, by any means, but I don't believe you are
correct on this point. Even the local first-tier support people can log
directly into the modem using what I believe they call PSV, peruse the
settings, readings, config, etc. Granted, the information they glean
appears to be rather limited - compared to the NOCs of other providers with
whom I've worked - but I think you are describing Comcast's support as much
more "in the dark" than they actually are.
...

I respectfully disagree with this generalization. I have been a technician
for seven years, and I used to operate a team of 13 telecom technicians. In
general, technicians try to solve problems to the best of their ability.
Your characterization is the exception, in my experience.
...

Several issues here. First of all, I have not had time to distill your
suggestions and put them into context. Secondly, Comcast is not simpy going
to execute every list of suggestions that might come their way. Third,
while I sincerely appreciate your willingness to help, and I respect your
expertise, I do not believe your earthing theory is valid. The reason is
that cable internet has been functioning perfectly in this location for
years. Only within the past 3 weeks have the problems arisen. While I'm no
electrician, I do understand the basics of electricity and grounding, and I
do not see how this factor bears on an internet connection's reliability
after working so well in the past. However, I may be missing something, and
I welcome your arguments to the contrary.
...

This is a valid question, and there is much to say here when I have a little
more time, but for now I want to ask: What are some examples of
problems on the subscriber side might cause intermittent internet?
...

And please clarify your suggestion regarding recording ping results from
subscriber side when connections are good and bad. Ping what? When the
internet is down, the Netgear [usually but not always] will not respond to a
ping, either from within or from the outside. Perhaps I've missed your
point.

Thank you for your determination to help.


.

Relevant Pages

  • Re: [Fwd: KI-2.6.8-2-686 Upgrage And Modem Issuse]
    ... KI-2.6.8-2-686 Upgrage And Modem Issuse ... Can you ping another computer by address ... My /etc/resolv.conf file contains both ISP supplied DNS servers. ... traceroute or host usage) but can under woody. ...
    (Debian-User)
  • Re: Internet Connection Sharing Problem
    ... Modem solved the problem. ... > other PCs show activity on their NICs with the same amount of data ... I can ping 192.168.0.1 but not google. ... >> to the LAN connection is fine, but it has to be in a different subnet ...
    (microsoft.public.windowsxp.network_web)
  • Re: My Router does not accept a gateway ip that has a subnet address different from the laptop ip ad
    ... Power everything down....modem, rtr, PC. ... Turn on the modem. ... posted were for the wireless connection. ... You can do ping tests again, ...
    (alt.internet.wireless)
  • Re: Re: XP Not Detecting Connection
    ... > ping requested address' or something like that 4 times. ... Make certain the patch cord from the computer to the cable modem is ... Also make sure household pets or rodents haven't been chewing on the ... between the desk and the wall (the cables, ...
    (microsoft.public.windowsxp.network_web)
  • Re: Cable Modem Issue
    ... >> I had similar problems with my Comcast supplied cable modem. ... Then booting modem and then router. ... > onto the internet and went to his e-mail. ... Your friend needs to learn how to use the ping command to test ...
    (microsoft.public.win2000.networking)