Cable Modem, Firewall Router, Network Troubleshooting

Discussion in 'hardware' started by TheKid7, Mar 21, 2016.

  1. TheKid7

    TheKid7 Registered Member

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    Does anyone have a good Troubleshooting Guide for determining and resolving Internet Connectivity Issues?

    Last Saturday there was a ~14 hour power outage where I live (heavy duty thunderstorms & lightning). I have everything (including the Coax cable) on Surge Protectors. I also have one PC, Cable Modem, Firewall Router and a couple of connecting unmanaged Gigabit Ethernet Switches on UPS's. I probably should have shutdown the two UPS's shortly after the power outage started but I decided to just let them go.

    When the power came back on Saturday afternoon, the Internet seemed to be working fine. The Internet seemed to be a little sluggish on Sunday Morning, but the connection seemed to go to a crawl when I tried to connect Sunday afternoon. I rebooted the Firewall Router and hard booted the cable modem and there was no improvement. I called the ISP's Customer Support and they instructed me to disconnect the Coax cable from the Cable Modem, disconnect the power to the Cable Modem, reconnect the Coax cable to Cable Modem and then reconnect the power to the Cable Modem. This seemed to fix the problem. However, this morning the problem was back. I tried hard booting the Cable Modem again as previously instructed by the ISP's Customer Support, but the problem was still there.

    I was in a hurry and decided to bypass the Firewall Router (PC->Switch->Cable Modem), but I apparently did not follow the correct procedure for establishing the connection. All I did was do an ipconfig /renew. I think that I needed to reboot the PC, but did not due to time limitations (I had to go to work.). I quickly reconnected everything and my Internet Connection was back and working properly again.

    It is easy for me to jump to conclusions. I suspect that it is the Cable Modem, but I do not know.

    Thanks in Advance.

    Edit: I think that I will purchase either an ARRIS 6141 or an ARRIS 6181 on my way home from work tonight. I have been renting a Cable Modem from the ISP for some time. I am sure it won't take long to pay for my own Cable Modem with the rental money savings.

    Correction: ARRIS 6183 not ARRIS 6181
     
    Last edited: Mar 21, 2016
  2. Bill_Bright

    Bill_Bright Registered Member

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    Do note when resetting your network, you have to unplug PCs from the wall (or flip the PSU's master power switch on the back of the PSU to off) to fully remove all stand-by voltages from the PC (including its NIC). Other networked devices may not truly power off unless unplugged too. Printers are a good example.

    This certainly could be a cable modem problem and that would be evident if local networking/connections worked fine but only your Internet traffic/connection was affected.

    I do recommend getting your own modem if you will be living there for awhile. But check your ISP's website. Most provide a list of compatible devices. I have the 6141 and it works great. You don't need the more expensive 6183 (not aware of a 6181) unless you have (or will be getting) extremely fast cable speeds above the very fast 343Mbps the 6141 is already capable of supporting.

    Depending on your ISP, you typically must call your ISP to register (authenticate) your new modem once installed. This usually is an easy process that takes only a few seconds (after you spend 30 minutes on hold before actually getting someone :rolleyes:).

    I recommend you disconnect and power off all your wired and wireless devices from your network. With all the power still disconnected, connect your network starting with just 1 PC via Ethernet to your router, then your router to your modem.

    At this point, I would call the ISP. Have the new MAC Address for the new modem handy. It will be listed on the new modem (though mine came with several extra stickers in the box so I didn't have to fumble with the modem while talking to the tech). Typically you provide the new MAC Address to your ISP, then you power up the modem, wait for the lights to settle down as it is authenticated by your ISP and receives its new IP address. Then power up the router and again, wait for the lights to settle down. Then plug in the computer power and boot it up. Verify you have Internet connection and be good to go, tell the ISP goodbye and then you can start adding your other devices.

    At least that is how it works with my ISP here. There may be other specific instructions on your ISP's website that may be slightly different but regardless, they will need the new MAC address. So being ready will make things go smoother.

    Oh BTW - kudos for using a UPS. IMO, all computers (and network gear) should be on a good UPS with AVR. Even with all your computers powered off, few UPS can sustain power to your network gear during a 14 hour outage. But the reality is, the bread and butter with a good UPS is the AVR. Backup power during a full outage is just the icing on the cake (for some reason, I'm suddenly hungry! ;)).
     
  3. TheWindBringeth

    TheWindBringeth Registered Member

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    @TheKid7: If you suspect the cable modem and/or external wiring/components, one thing you can do is look at the cable modem's admin page (http://192.168.100.1, http://192.168.0.1 or whatever) and see what diagnostic information is available. You may need to do research in order to understand some of it, but it can be useful.

    Some data may be of a nature that you'd want to watch how it changes over time. A simple script that periodically fetches and saves an admin page to an incremented filename every N minutes would be crude but sufficient.

    Ipconfig /release followed by ipconfig /renew is often what one wants to do.

    BEFORE you connect your new cable modem to the cable network, connect it to your network and check the admin page. Save info about the original firmware. This may help you determine if/when the cable company updates the modem. At some point, attempt to determine what version you should have (check cable company forums) and verify that you have received it.
     
  4. TheKid7

    TheKid7 Registered Member

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    I went to Walmart at lunch time and picked up the SB6141. Walmart had the price ~$10 higher in-store than online and it took me a while to get them to lower it to $69.99. I should be able to install the SB6141 this evening.

    Can anyone recommend a high quality and best value Coax Cable Surge Suppressor? For future, I would like to have something better than the ones that came with my Surge Supressors.
     
  5. Bill_Bright

    Bill_Bright Registered Member

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    Some UPS have them. I don't use surge and spike protectors as they are little more than fancy and expensive extension cords. I rely instead on a "good" UPS with AVR.
     
  6. TheKid7

    TheKid7 Registered Member

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    I successfully installed the new Cable Modem and had the ISP enter the MAC address for it. However, I still had essentially the same problem.

    After being frustrated for some time, I decided to completely bypass my the Cable Surge Protector and I forgot that I also had a Cable Signal Splitter in the line that was no longer needed. The problem went away. I have full bandwidth now. I am guessing that lightening generated by the unusually bad Severe Thunderstorms had probably weakened the signal some to my residence and/or somewhat damaged my Cable Surge Protector/Cable Splitter.

    I plan to order a Cable Modem Surge Protector (TII 212) today and install it. This should not weaken the signal significantly. I want something in the line for Surge Protection. I just need to figure out how I am going to ground it.

    http://www.tiitech.com/products.php?cat=7

    http://www.tiitech.com/repository/datasheetlibrary/210_212.pdf
     
  7. Bill_Bright

    Bill_Bright Registered Member

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    I had an instructor once who said surge and spike protectors were like motorcycle helmets, when they save your noggin once, they did their job and need to be replaced. While there may be no apparent physical damage, they likely have been weakened.

    Those protectors were not what I was thinking about when mentioned in your previous post. I would think you should have one of those protectors where the service enters your home. At least, that is where mine is and it was put there by my cable provider.

    You are right, any signal degradation will be insignificant.

    BTW, when your ISP authenticated your new modem, they should have indicated then you had good (or lousy) signal. I should have asked earlier (sorry!), but are all computers in your home behaving the same way? Have you scanned for malware?

    While there are way too many variables to set a standard, what is your average ping rate when open a command prompt and enter: ping www. yahoo .com (without the spaces) then press enter.

    Check your speeds with Speedtest.net and Testmy.net. Then check your contract to make sure you are getting what you pay for. If not, contact your ISP and complain. Hopefully, the contract states a minimum and not something vague like “up to” some speed.
     
  8. TheKid7

    TheKid7 Registered Member

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    The ISP Customer Support did not mention anything about signal strength. When I get a chance I may give them a call. I did briefly log into the new Modems Web UI, but I did not notice if the Cable Modem gave the Signal Strength. I will log into the Cable Modem's Web UI when I get a chance to see if the Signal Strength is shown.

    No Malware.

    All of my Computers seems to be functioning normally. I forgot to check my TV Tuner Card which is protected by the exact same type of Coax Surge Protector as the Cable Modem's Surge Protection. I will check it to see if the TV Tuner seems to be working OK when I get a chance.

    I did a Speedtest with my ISP Speed Tester (http://mygrande.com/internet/speed-test)(I think that I actually used this speed tester which is supposed to be for 100 Mbps+: http://speeds.mygrande.net/) and got an average of ~52 Mbps download. I am paying for 50 Mbps download. The Upload speed looks reasonable but I don't remember what is specified for my ISP Plan. I did notice that the same Speedtest before there was an indication of any problem and with the old Cable Modem gave a similar average download speed but was more smooth (less sawtooth shaped) than the current Speedtest with the new Cable Modem. I did not try to quantify the severity of the sawtooth shape but I would guess that the lowest dips (minimum's) were around 45 Mbps (possibly as low as 40 Mbps). I will retest when I get a chance and look more closely at the minimum values.
     
  9. TheKid7

    TheKid7 Registered Member

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  10. Bill_Bright

    Bill_Bright Registered Member

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    Signal "strength" is not really the proper term. But they can measure latency and bandwidth to ensure you are getting what you pay for. If you are paying for 50Mbps second and getting 52Mbps, not likely the ISP will do anything about it.

    As far as you solution, I frankly am not crazy about that grounding probe. It assumes too much, IMO. It assumes the wall outlet is properly wired and grounded all the way to a solid "Earth" ground past the service panel. That's a lot to assume for lightning protection. That protector should be mounted outside the house, near where the cable comes through the wall. There should be a solid copper, 6 or even 4 (smaller number = bigger wire) gauge grounding wire connected to the protector that runs directly (no breaks or slices) to a 6ft (8ft would be better) grounding rod pounded nearly all the way into solid earth. A wall outlet's wires typically go through several junctions along it's circuit, any one of which could have a loose screw making for a lousy (if not dangerous) ground scenario. :(

    If your cable enters the home near where your cold water copper (not PVC) pipe enters your home, you can ground it to that IF 100% certain the pipe runs direct into the ground with no valves in between.

    If you absolutely have no choice but to use that probe to a wall outlet thingy, I would urge you to get an AC Outlet Tester to ensure your outlet is properly wired and grounded. In fact, every home and every computer user should have access to one. I recommend one with a GFCI (ground fault circuit interrupt) indicator as it can be used to test bathroom and kitchen outlets too. These testers can be found for your type and voltage outlet, foreign or domestic, at most home improvement stores, or even the electrical department at Walmart. And if a fault is shown, have it fixed by a qualified electrician.

    BTW, if your TVs are getting good clean video and noise free audio on all your cable connected TVs, that typically indicates the cable wiring itself is good.

    Also, note your Grande Speed Test uses the Ookla service which provide the Speedtest.net test above.
     
  11. TheKid7

    TheKid7 Registered Member

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    I installed my homemade Coax Surge Protectors this morning. However, I forgot to login to the Cable Modem to look at Signal Strengths prior to installation. The following are with the new homemade Coax Surge Protector installed.

    Downstream Bonding Channel Signal/Noise Values (8 Channels): 7 are 37 dB, 1 is 38 dB
    Normal Range (*): Signal/Noise Ratio (SNR , >30dB)

    Downstream Bonding Channel Power Values (8 Channels): 2 are -1 dBmV, 2 are -2 dBmV, 4 are -3 dBmV
    Normal Range (*): Downstream Power (-15dbmV to +15dbmV)

    Upstream Bonding Channel Power Level (3 Channels): 44 dBmV, 47 dBmV, 48 dBmV
    Normal Range (*): Upstream Power (37dbmV to 55dbmV)

    (*) Normal Range Values given above are based on the values given in the following web page.

    http://www.speedguide.net/faq/what-cable-modem-signal-levels-are-considered-good-78
     
  12. Bill_Bright

    Bill_Bright Registered Member

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    I would compare it with your speedtest results again. Of course these can vary throughout the day, but it should give an idea if the suppressor is making things worse.
     
  13. TheKid7

    TheKid7 Registered Member

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    I just ran the speed test. This morning's speed test graph was very smooth (both download & upload) compared to the other day. The text of the Speed Test results is a follows:

    Download Speed: 52658 kbps (6582.3 KB/sec transfer rate)
    Upload Speed: 5358 kbps (669.8 KB/sec transfer rate)
    Latency: 23 ms
    Jitter: 4 ms
     
  14. Bill_Bright

    Bill_Bright Registered Member

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    Looks great!
     
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