Problems with upgrade to Surfboard SB8200 modem

Discussion in 'TiVo Roamio DVRs' started by JVOLLEY1, May 13, 2017.

  1. JVOLLEY1

    JVOLLEY1 New Member

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    Nov 24, 2005
    I just upgraded by modem from Surfboard SB6141 to Surfboard SB8200. I can access internet when the coax cable is connected directly to the modem, Ethernet connected to the Netgear N900 Wi-Fi router, but I can't get a TV signal through my TiVo Roamio Pro (which I shouldn't). When I connect the coax cable from the wall to a two-way splitter with one coax going to the modem (ethernet cable connected to Wi-Fi router) and one coax going to TiVo, I get a TV signal, but no internet access. This is the setup I had with the Surfboard SB6141 which worked without any issues. Attached is a portion of my current network diagram. Does anyone have any ideas?
    Network Diagram.jpg
     
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  2. kpeters59

    kpeters59 Well-Known Member

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    Houston, Texas
    So, you're saying that you unplugged your old modem and plugged in your new modem and the TiVo quit receiving cable TV?

    That'd be odd...

    Did you unplug everything, or maybe explain what else might have changed?

    My internet went out a few weeks back, but my TiVo, connected to the other half of the splitter, was fine. Went through a BUNCH of steps, before it turned out to be a nasty corroded splitter outside at the Comcast building panel.

    What is your TiVo signal strength levels like? If you un-plug the modem does the TiVo begin receiving again?

    More details would be helpful...

    Thanks,

    -KP
     
  3. JVOLLEY1

    JVOLLEY1 New Member

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    Nov 24, 2005
    I didn't do a good job of explaining this. I notified Comcast when I installed the new modem so it could be provisioned. I do get a TV signal, and internet, but not at the same time if that makes sense. Based on my diagram with the old modem I would connect the coax cable from the wall plate to a 2 way splitter; from the splitter I would connect a coax cable to the TiVo and a coax cable to the modem and connect a Ethernet cable from the modem to the WiFi router and all was good. I replaced the modem with a newer modem and now I can't get internet with this setup. I can only get internet when I connect the coax cable from the wall plate directly to the modem (without splitter), but then I don't get a TV signal. Does this make any sense?
     
  4. kdmorse

    kdmorse Well-Known Member

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    Wild swag - the SB8200 is using a different set of upstream (or downstream channels), as it is DOCSIS 3.1 compliant. Comcast is attempting to push people to DOCSIS 3.1 modems so they can provision them into a different range of channels, and alleviate pressure on the channels that DOCSIS 3.0 modems can see. And these new channels are conflicting with the MOCA signaling the Tivo's are using to communicate.

    While your old config worked, you should generally have Point of Entry -> Splitter, with your Cable Modem on one leg, and your other devices on the other, behind a MOCA filter.

    (Just checked, frequency overlap between DOCSIS 3.1 and MOCA is a known problem)
     
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  5. JVOLLEY1

    JVOLLEY1 New Member

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    Nov 24, 2005
    kdmorse, thanks for the information. I turned off MoCA on my TiVo and everything is working with the exception of my TiVo minis. Is anyone successfully using DOCSIS 3.1 and MoCA?
     
  6. kpeters59

    kpeters59 Well-Known Member

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    Houston, Texas
    Maybe try forcing MOCA to either the highest or lowest frequency channel you have available to see if that helps.

    -KP
     
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  7. fcfc2

    fcfc2 Well-Known Member

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    My guess would be to try the highest MoCA channel, but without knowing for certain what frequencies are being used by the 3.1 modem, it is just a guess or a series of trial and error guesses to see if any of the available MoCA channels will work. Another option would involve some rewiring (coax) to isolate the line going to the 3.1 modem and connecting everything else Tivo DVR and minis on a separate coax network with the MoCA filter being on the input to that section(s). Option C, go with a non-docsis 3.1 modem, with something like the Netgear CM600, a 24x8, if this will support the speed tier you want.
    Here is a link with a pretty clear explaination of the conflict,
    MoCA vs. DOCSIS 3.1: Whose Spectrum Is It?
     
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  8. krkaufman

    krkaufman TDL shepherd

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    The long-term solution is a dedicated coax line for your DOCSIS 3.1 modem, but you may want to try @kpeters59's suggestion to try manually setting your MoCA channel, above the iniitial DOCSIS 3.1 rollout range...

    [​IMG]

    ... so probably channel 21 or higher:

    15: 1150 MHz
    17: 1200 MHz
    19: 1250 MHz
    21: 1300 MHz
    23: 1350 MHz
    25: 1400 MHz
    27: 1450 Mhz
    29: 1500 MHz
     
  9. Jed1

    Jed1 Well-Known Member

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    I severely doubt that Comcast has any systems that are broadcasting above 1Ghz. At best Comcast will have 16 to 24 downstream channels and the Arris SB6183 is well suited for those applications. The modem you have is not a MoCA device and only receives what Comcast already has on its system. If there was activity above 1Ghz that would exist even without this modem.
    The Arris SB6190 has a known issue with the Puma chipset in it so it is possible that the Arris SB8200 has the same chipset with the same problem.

    Put this address in your browser and it will bring up the status page so you can see how many channels the modem is locked onto and what frequency they are at. If you do a print screen and paste that in MS Paint and save it you can post the picture of the page here.
    http://192.168.100.1
     
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  10. krkaufman

    krkaufman TDL shepherd

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    What about just putting a MoCA filter on the input of the SB8200?

    With a MoCA filter installed at the point-of-entry in the OP's existing setup, blocking any signals above 1GHz, I'm starting to think it's more likely that the SB8200 just doesn't like the MoCA signals.
     
  11. fcfc2

    fcfc2 Well-Known Member

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    My new theory is that the SB8200 is simply not MoCA friendly, meaning that it and probably all Docsis 3.1 modems will not have a MoCA filter builtin like most of the Arris SB6xxx series do. My guess is that if potentially increasing the number of channels in use to over 1GHz is part of the 3.1 specification, then no manufacturer would want a MoCA filter builtin. If I am correct, simply adding another MoCA filter on the input of the SB8200 should make the problem disappear until and unless the full 3.1 system is implemented.
    PS. I think the SB8200 is not Puma 6 and the problem with it is related to "latency" not simple connectivity.
    EDIT: Kaufman beat me to the trigger, but I think we agree, and the additional filter will either confirm or deny the theory.
     
  12. krkaufman

    krkaufman TDL shepherd

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  13. krkaufman

    krkaufman TDL shepherd

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    Precisely, since the DOCSIS 3.1 signals are in the MoCA range, they pretty much cannot have a MoCA immunity filter built-in... and the modem may well be trying to ~decypher~ the MoCA signals as DOCSIS 3.1... and failing.

    Yep. And I'm confident the 2nd MoCA filter, installed on the input of the SB8200, will resolve the problem. (It'll be entirely new territory if not.)
     
  14. Bigg

    Bigg Cord Cutter

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    I agree with fsfs2 and krkaufman here. The modem is spec'ed for a 1.2ghz full capture tuner, and the MoCA signals are throwing it for a loop. Put a MoCA filter on it that cuts off at 1002mhz at the highest, and everything should work just fine. If the OP is in Colorado, it's possible that it is a 1.2ghz N+0 plant, otherwise I believe Utah has some at 1002mhz, and the rest of the US is 860 or 870mhz upper end, with some local systems' upper ends being at 550mhz, 625mhz, 650mhz, or 750mhz. On a 625mhz system, you don't need a MoCA filter at all, as there is no risk of the plant passing MoCA signals.

    Due to this issue, and the wide use of MoCA in MSO DVRs, the SB8200 really should come with a MoCA filter in the box. It has to be separate or otherwise removable, as some day, there could, theoretically, be cable plants up to 1200mhz that could interface with the SB8200. These would likely be N+0 fiber-deep plants, as the current HFC infrastructure pretty much starts to go haywire above 860mhz.
     
  15. Bigg

    Bigg Cord Cutter

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    I went and read DSLReports, and they are upgrading some systems to N+0, but it's not clear from my skimming if any of them are running above 860mhz or 1002mhz.
     
  16. JVOLLEY1

    JVOLLEY1 New Member

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    Nov 24, 2005
    Sorry I haven't responded sooner, have been pretty busy. I installed a MoCA filter at the back of the modem and MoCA is working again. I have a question about the MoCA adapter and TiVo Mini. If I install a MoCA adapter in the office to connect a PC and TiVo mini would I need to install a switch and connect to the TiVo mini with Ethernet?
     
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  17. krkaufman

    krkaufman TDL shepherd

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    You could either do that or use a MoCA-compatible coax splitter to connect both the Mini and new MoCA adapter to your coax lines. (You would NOT be able to connect the Mini to the MoCA adapter's "TV/STB Out" port, if it has one, as this port doesn't pass MoCA signals.)
     

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