Cable internet signal strength…

Discussion in 'Technical Corner' started by Bell206, Feb 8, 2019.

  1. Bell206

    Bell206 Cleared for Takeoff

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    Does anyone know the proper method to check internet signal strength at an origin point (house interface box) and what type equipment to use?

    I’ve been troubleshooting a speed issue with my cable internet (Cox) after several service interruptions since Dec 2018. Cox wants to charge to come out and check speeds as their internal “ping” tests show no issues.

    I’m looking to verify/compare whether the signal changes after entering my house or it starts out weak at the source. I also plan to compare to other signals in the neighborhood. I understand there will be strength differences based on the overall usage of the various systems.

    FYI:
    Upgraded my modem (SURFboard SB6141) and router (Nighthawk AC1750) end of 2017. Everything work great until Dec 2018 when there were several service interruptions over a 3 week period. Since then it appears the system is operating at sub-gigabit speeds.

    After some reboot issues following each outage, the modem link status light remains amber (10base/100base) instead of blue (1000base) as it had been since the upgrade/interruptions.

    I’ve verified firmware versions, rebooted/reset, and sent error/data logs to the modem tech support. Per the techs, the logs they reviewed indicate a signal strength issue with the provider or my home distribution network.

    Aside from the amber modem light it appears some large downloads are lagging also. I never ran a speed test after the upgrade as didn't have a reason. But current values average 9.4 Mbps down and 6.8 Mbps up on the Preferred service (up to 50Mbps down/5Mbps up).
     
  2. EppyGA

    EppyGA Touchdown! Greaser!

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    It requires a Digital Signal Level Meter capable of reading QAM levels. Cable is designed to have a certain level, measured in dbmv at each tap port. to arrive at that number a system has to determine the average drop length to the house and average number of devices (splits) they want to design to in the house. Digital devices, such as modems, will work with a lower level than analog TV's will.

    You reference a link light only showing 10/100 and not 1000. Is that a link light on the cable side or the E-Net side of the modem?

    This link will tell you a lot about the DOCSIS specs https://en.wikipedia.org/wiki/DOCSIS

    I'm not sure how many operators have upgraded to DOCSIS 3.1 at this time. Most are probably at least at 3.0.
     
  3. Kenny Phillips

    Kenny Phillips Cleared for Takeoff

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    Our signal was weak, causing occasional dropouts [when Spectrum took over TWC]. Not good if working from home. The repair man with the meter went from the street to my house, and inside my house, measuring it at every junction (it's maybe 600 feet from the pole to my modem, with an underground portion as well.) There was no single smoking gun; he replaced every single connector, and gave us a modem that he knew worked better with a weak signal. No problems since.
     
  4. weilke

    weilke Touchdown! Greaser! PoA Supporter

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    Some modems allow you to directly read signal strength and parameters like frames lost etc.

    I 10/100 and 1000 and the different LED colours would seem to be nomenclature that relates to the ethernet issues. Are you sure this link light is for the cable side of things ?
     
  5. Skip Miller

    Skip Miller En-Route

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    Let the competition do it. Call up a competitor and sweet talk them into coming out and measuring your current performance. Tell them that if they can do materially better, then you will consider switching.

    Then take their data and have a heart to heart with your existing carrier....

    -Skip
     
  6. Raymo

    Raymo Pre-takeoff checklist

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    Plug directly into the cable modem and run a speed test. If that is better, move to the next device in line and test again. I had a similar problem recently and it turned out to be a bad laptop base (C-Port type). Swap it for a new one (company owned) and problems are gone.
     
  7. weilke

    weilke Touchdown! Greaser! PoA Supporter

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    Cable.

    Competition.

    Lol.
     
  8. -KLB-

    -KLB- Pre-takeoff checklist

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    The only affordable tool at the consumer level is a cable modem with a password you know. Most of them, if you are connected behind them have a user interface at 192.168.100.1. Often they are at factory default passwords that are easy to google. You can take the modem and laptop to different places and check the signal strength as reported by the modem.

    Note that I would not try at any neighbors connections. Without their permission, you could interrupt their work from home day, or their favorite soap recording on the DVR. And with how common security cameras are, this could lead to federal charges. Even with their permission, if the cable company hears about it, they could file theft of serices charges, simply because you connected to a port you were not paying to use. So you may not gain any advantage knowing how it compares.
     
  9. Heftiger

    Heftiger Pre-takeoff checklist

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    I run into problems like these with ISPs and vendors all the time. Nobody wants to help unless you spend hours tracking down the issue so you can PROVE it’s their problem. Very frustrating to deal with. I should bill them for my troubleshooting time.
     
  10. RJM62

    RJM62 Touchdown! Greaser!

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    Try going to http://192.168.100.1/ . It's a pretty common address for cable modem Web interfaces.

    Rich
     
  11. bflynn

    bflynn En-Route

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    Not sure if it's helpful, but here's the signals page from my modem. This is a Motorolla 86121. It cost $65 when I bought it many years ago and has more than paid for itself in saved equipment fees from the cable company.

    modem_signal.JPG
     
  12. Bell206

    Bell206 Cleared for Takeoff

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    Appreciate all the responses. Here's some more answers.

    I don't know on the what side the link is. I looked in the manual and based on the note below about the "blue" indication, plus what the Arris tech said it will only turn blue if a device is connected to the ethernet and high speed service is available. Otherwise it stays amber. The link was blue up until last Dec (1 years time).
    upload_2019-2-8_15-21-55.png

    The Cox service is DOCSIS 3.0. It was one of the reasons I upgraded the modem/router.

    Did that but saw no improvement. Next step was to go farther upstream but thought I might inquire here 1st to see if there was a portable tester I could use instead.

    I've checked the modem signal values as seen through the 192.168 IP address. But interpreting this chart is out of my skill set. It was after emailing these signal logs/values to tech support that they suggested I might have a signal strength problem with the provider or within my home network.

    Comparing my signal stats (below) to the charts bflynn posted above, I find some values similar and some not. But I don't know what I'm looking for.

    It was suggested to me to first check the internet signal at the home interface box then follow the signal into the house and see if it degrades. If this means I need to walk around with my modem and laptop okay. But I figured there has to be a simpler method to check the signal strength at different points--something like my Klein VDV Scout cable tester. It doesn't need to be accurate at this stage just give a value I can compare at different points.
    upload_2019-2-8_15-28-46.png upload_2019-2-8_15-29-21.png

    Only with their knowledge. The only intent was to generally compare signal strength at their interface to mine.

    Ha, I wish. The only competition is satellite.

    Thanks.
     
  13. EppyGA

    EppyGA Touchdown! Greaser!

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    You don't have a level issue. The levels you are seeing are within range for the device. The SNR numbers are excellent.

    The explanation from your book is surely confusing concerning the light. I'm not sure why the Ethernet side being 10B1000 should matter a bit on the cable sides capability. That sounds really dumb. Is all your other gear in the house 10B1000 capable?
     
  14. weilke

    weilke Touchdown! Greaser! PoA Supporter

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    The speed on that auto-sensing port is determined by the speed of the thing you plug it into. It would seem odd for your router to fall back from 1000 to 10/100. It should not be in any way related to the speeds your cable modem sees on the cable company side of the box. However, the manual seems to suggest that that is exactly what it does. Very odd behavior if true.
     
  15. Bell206

    Bell206 Cleared for Takeoff

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    By that do you mean the signal strength value shown on the modem stats page is at acceptable levels?
    Yes. When I went to the 3.0 modem I upgraded the router and replaced the 2 switches I have with TP-Link Gigabit switches.

    I had several reboot issues during the Cox service interruptions that led me to do factory resets on both the modem and router. However, the amber light has stayed consistent since the first interruption. Maybe I have an internal router issue? I checked the router config page and everything seems still on the default settings as stated in the manual, to include all ports on "auto-sensing" if that is applicable to this problem.

    FYI: I'm about to finish up relocating some of the network components as soon as I complete building new CAT and coax cables. I think I'll comply with a fresh reset on the modem/router/switches when I move them. Maybe the blue light will come back then. If not I'll contact Netgear/Arris with some log reports and see what they say. If I'm still lost will try back here. Thanks.

    In the meantime, if anyone else has any other input it will greatly appreciated.
     
  16. EppyGA

    EppyGA Touchdown! Greaser!

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    Yes, those are probably good down to -3dbmv and still give acceptable performance.
     
  17. 455 Bravo Uniform

    455 Bravo Uniform Pattern Altitude PoA Supporter

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    Can some of the “house side” equipment (modem) go partially bad and still work, but slowly? Are there firmware checks or patches that might be out there for known issues?
     
  18. weilke

    weilke Touchdown! Greaser! PoA Supporter

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    Is there a switch between the modem and the router ?
     
  19. Lantraxco

    Lantraxco Pre-takeoff checklist

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    I don't think the modem "falls back" at all, but in order for the LED to turn blue you have to have both sides operating at Gigabit speeds. Plug your laptop into the modem directly and bring up the network connection, it will tell you what speed you're connected at locally. Hell maybe you got a porn server on the same cable segment and they're eating up all the bandwidth 24/7?
     
  20. cowman

    cowman En-Route PoA Supporter

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    It sounds like your light going from 1000 to 10/100 is on the ethernet(house network) side of things. My first thought is you either have a cable that's got a poor connection or interference somewhere- network gear will automatically downgrade from a GB connection to 10/100 if it has signaling problems but that's on your side of things not the cable company's.

    1000 is refering to 1000Mb/s or 1GB. 10/100 is the older standard referring to 10Mb(really old) or 100Mb. I suppose if your link between the modem and the rest of the network was dropped all the way down to 10Mb it would explain why you're getting < 10Mb down since that would be the slowest link in the chain.

    Are you directly plugging your PC into the cable modem or does it go to a router? If it goes directly to a PC you can view the connection speed of the cable in windows. In windows 10 you have to go to the network and sharing center, then click the blue link "ethernet" next to your network and it should pop a window giving the link speed. On a router, IDK depends on the make/model. Either way the first thing I'd try is swapping the ethernet cable that's between either your pc or router and the cable modem with a new/known good one.
     
  21. Bell206

    Bell206 Cleared for Takeoff

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    No. The wireless router feeds 3 cables: 1 provides a hardwired "guest" port in the kitchen; 1 connects the "house" switch which feeds entertainment equipment; 1 connects my "office" switch which feeds 2 docking stations, an NAS, and connects a printer. But all checks have been done with these 3 LAN cables disconnected.

    I had done this back in Jan a few times but still had the amber light and the same speed test values. Unfortunately I have no speed test results from prior to the service outages. However, tomorrow morning I will disconnect everything and connect laptop direct to modem and check again.
    Ha. But it would have to be the old lady's doing. Maybe she has a secret server in her bathroom closet?:eek2:

    I've swapped all cables several times and even fabricated some new ones. But no change. I even ran a new coax to the modem.
    I've gone laptop direct to modem but no change. However, I will check laptop to modem again tomorrow morning and report back.
    I have Windows 8.1 Pro on a Dell Latitude E5440. Will the network/sharing center be the same?
    Netgear Nighthawk AC1750 (R6700)

    I've got some computer work to finish up today but will perform new checks tomorrow starting with laptop to modem and go from there. Thanks again for the help.
     
  22. weilke

    weilke Touchdown! Greaser! PoA Supporter

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    Pick up a standalone cable modem at a retailer with a good returns policy and test it with that. At the offices I rent the cable modems from the cable company and they seem to get wonky and die every other year. Cable guy comes, replaces the modem and we are fine for another year or two. They seem to wear out.
     
  23. Spring Ford

    Spring Ford Pre-Flight

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    Just had a crazy thought.

    If I recall correctly, Gigabit Ethernet uses all 4 pairs of a cat5 (say) cable and 10/100 uses two pairs only. A particular two pairs. I would guess that if one of the 4 wires in the extra pair was not connecting that the connection would fall back to 10/100.

    I concur that you appear to have a good cable connection.

    The worst channel has a downstream error rate of 1 in 438 million unless the counters have overflowed in which case it will be even better. That is outstanding.
     
  24. cessna182b

    cessna182b Line Up and Wait

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    Not always. I had a problem like the OP describes. My old reliable Motorola cable modem started dropping out - intermittently. I replaced it with a new one - which
    worked fine - for a while. Then it started dropping out as well. I called the cable company and they sent a guy out with the appropriate level meter. He quickly deduced
    that my feeder cable (which was buried) was going bad. Probably water intrusion - but that's only a guess. To my amazement, they replaced the buried cable at no charge!
    End of problem!

    Dave
     
  25. EppyGA

    EppyGA Touchdown! Greaser!

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    You can always try going out to the ground block (that's where the incoming drop is grounded) and disconnect both sides and then screw them back on.
     
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  26. Bell206

    Bell206 Cleared for Takeoff

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    Ran a few checks this morning and encountered several other issues.

    Right now I don’t think I have a Cox signal strength issue based on the collective consensus here and these other quirks. If there is a signal problem I’ll deal with it later after I fix the system

    First, I could not connect my laptop directly to the modem (but could back in Jan/Dec). I kept getting a “connection 1602 error” which per online T/S info required a restart of the Windows Event Log. After I did that when I went to connect rec’d a “651 error.” However, I think this whole issue may be self-induced as I tried to get a serial port-USB adapter to work 2 weeks ago to download some vibration files off an old vib checker. As such, I played with certain laptop configurations which were at the edge of my skill set and may have done something incorrectly. Will check on the laptop to modem issue later.

    Moving on, I swapped cables and did a few more reboots/resets on the modem/router with no change: amber light on modem indicating 100/10M signal with same internet speed levels. I also put a Giga switch in between the modem and router to see if it would force something. The only thing noted was the modem/router attempted to connect based on the link/internet LEDs but no connection could be made. Don’t know if this means anything, but when I hot swapped cables back from the switch, modem direct to router, no connection was established. Had to reboot modem to reconnect to router.

    Did some digging in the router manual and found how to check port speeds. Bingo. The WAN port is showing 10M with the one LAN in use showing 1000M.
    upload_2019-2-10_10-45-54.png
    So now my question is the router capping the signal at 10M or is the modem limiting it?

    I checked the logs on the modem for any new msg but only noted the same msg I usually get when I reboot. And nothing noted on the router logs out of the ordinary. However, I can post those if it will help.

    In the meantime, I plan to borrow another high speed router to see if the 10M input changes. And I also plan to contact Netgear support on the WAN 10M issue to get their input as I haven't done that with this issue.

    But will appreciate any more guidance you guys can offer.
     
  27. RJM62

    RJM62 Touchdown! Greaser!

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    As Randy said, checking / cleaning the ground block is easy to do and has been known to solve all sorts of issues.

    You my also want to ask your ISP to unregister and reregister the modem.

    Having to reboot the modem whenever you change the downstream interface is normal. The IP as assigned to the MAC of the first downstream device. So when you change it, you essentially have no IP address assigned to you.

    Rich
     
  28. Bell206

    Bell206 Cleared for Takeoff

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    By this you mean the incoming coax cable at the exterior interface box? If so I cleaned both ends of grd wire. It was tarnished but still shiny at set screws. How sensitive is this ground connection? Should I disassemble the entire main ground rod assembly and clean all contact surfaces? The coax ground was connected at same place phone ground was which I cleaned/tighten both.

    I'll do that this week.
     
  29. EppyGA

    EppyGA Touchdown! Greaser!

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    The ground may not be the problem, it could be some slight corrosion on the coax connectors on either side of the ground block. Disconnect the coax connectors on both sides and then connect them back.
     
  30. RJM62

    RJM62 Touchdown! Greaser!

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    It's usually not so much the ground as the block itself and the F connectors on the cables (although bad grounds can also cause problems). Unscrew the coax from both ends of the ground block, spray both connectors with some electrical contact cleaner, spray some of the contact cleaner through the ground block where the fittings attach, and reassemble it.

    If the core wire of the coax is corroded, then I'd have someone cut off and replace the connectors. Make sure they use weather-proof connectors (the compression type). I'd probably replace the ground block, too, if the coax is corroded. If there's corrosion on the coax, then there probably is inside the ground block, as well.

    None of this is necessarily going to solve the problem, by the way. It's called ruling out the easy stuff. Bad grounding blocks and corroded connectors can cause all kinds of problems.

    Rich
     
  31. Ghery

    Ghery Final Approach

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    You remember correctly. 10 BASE T and 100 BASE T only use 2 of the 4 pairs in a CAT 5 cable. 1000 BASE T uses all 4 pairs.
     
  32. Bell206

    Bell206 Cleared for Takeoff

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    Done. The F connectors looked good. I've been fabricating all types coax for years, but didn't see reason to change these (they were compression type). Cleaned and reconnected. Also applied some top-shelf contact enhancer. Tested cables on both sides--found good. Also with everything disconnected megged the ground block to the master ground rod--good.

    My middle name.

    I posted the router's WAN 10M/Full issue on the Netgear community as my free tech service ran out 4 months ago. But I still have 6 months leave on the hardware warranty.

    Does anyone have any additional checks I can do to try and determine why the router is only seeing 10M at the WAN port? Only 10M will definitely make the modem light stay amber.

    I wonder if my router went TU during the service outages?

    Hopefully I'll have another Giga router here this Friday and we'll see what gets from the modem.

    Thanks again for all the help.
     
  33. -KLB-

    -KLB- Pre-takeoff checklist

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    Be sure to try a new Ethernet cable as well. Even certified cables can be bad, as all they do is test the spool from the end, and test samples of the connectors and assembled cables, then they get to call the lot “certified”.

    Back when I had access to $20,000 in cable test gear, including cat6 patch cable testing, I found I could use cat5e stranded cable, with cat6 plugs, up to about 20 feet that were significantly more likely to pass test than commercial certified cat 6 patch cables.
     
  34. Bell206

    Bell206 Cleared for Takeoff

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    I think I'm on my 10th cable: store bought and fabricated. Did find one cable that flunked continuity test so it got filed. But no change. Thanks.
     
  35. EppyGA

    EppyGA Touchdown! Greaser!

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    Time to tell the provider to come fix it.
     
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  36. Raymo

    Raymo Pre-takeoff checklist

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    Sounds like either the cable modem or your router is failing to negotiate correctly. If both sides are set to auto-negotiate, they should negotiate the highest speed possible at full duplex. Many think they can force the connection speed by setting one side to 100/Full or 1000/Full but this WILL disable negotiation on the side that is so set and you will get either 10/half or 100/half along with a duplex mismatch and extremely poor throughput.

    When you connect your laptop, be sure to reboot the cable modem. If your modem cannot connect to your laptop or standard switch, I'd suspect it is the problem.
     
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  37. Spring Ford

    Spring Ford Pre-Flight

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    [​IMG]

    This would very nicely explain the symptoms reported.

    I forgot that I had spent years of my life explaining this to people who were very reluctant to listen. (Sorry desktop/server fixers)

    Both sides MUST be set to Auto speed/Auto duplex.

    OR

    Both sides must be hard coded the same speed and duplex. THIS IS NOT RECOMMENDED since nothing made in the last 12 years or more will need it and someone will eventually forget and you will have a hard to diagnose issue absent professional level kit with accessible error counters and someone prepared to look at them.
     
    Last edited: Feb 13, 2019
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