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Coreyhrpr's avatar
Coreyhrpr
Aspirant
Mar 27, 2020

CM1000 v2 Modem - Comcast gig speed

I have the CM1000 v2 running as my modem, and I have comcast as the provider.

My speeds range between 300 - 400 mbps but I have the 1 gig plan. I called Comcast and the tech said its because I have Docsis 3.0 and Docsis 3.1 on the modem and that I need to have Docsis 3.1 only inorder to get my gig speed. He suggested I call Netgear to see about turning off Docsis 3.0. He said I should make sure I have the latest firmware as well, but I told him that Comcast pushes out the firmware, which he firmly denied that they do. With the limted settings I can control on the CM1000 model itself, should the CM1000 v2 be compatible with Comcast and be able to get the gig speed Im now paying for? Shouldnt the Docsis 3.1 work? Is there anyway to turn off the Docsis 3.0?

 

CM1000 v2 Modem Firmware Version V6.01.06

Netgear R8500 Wifi - Router

TP-Link PCIE gig network card

All Cat 6 Cables - and hardwired in

Computer is dual Xeon E5520 @ 2.27Ghz processors

8 gigs of Ram

Windows 10

 

I'm at a loss as I feel like the agent at Comcast doesnt know what he is doing, and I'll have to call back and wait another 2 hours for someone else.

 

Any help is appreciated

4 Replies

  • plemans's avatar
    plemans
    Guru - Experienced User
    Mar 28, 2020

    You're right. He didn't know what he was doing. I've got a CM1000 and CM1100 and used both on comcast without issues. You should have 31-32 channels locked on downstream, I think 4 on upstream, and 1 ofdma. plus the signal needs to be optimal. 

    Do you have a screen snip of the modems connections page? 

    and how are you testing speed? many speedtest sites can't max out speed. 

    • Coreyhrpr's avatar
      Coreyhrpr
      Aspirant
      Mar 28, 2020

      Thanks for the reply.

      I attached a screen shot of my connections from the CM1000.

       

      Also I've been testing the speeds through various situations - all wired in. 1. using an older PC and two using my surface computer.

      I've tested it through the Netgear NighthawkR8500 router and also directly through the CM1000 modem.


      I've used Comcast's speed test and the Speed Test by Ookla (speedtest.net). I've tried a variety of servers as well on speedtest.net.

      All in all the speed tests are about the same. 300 - 400 through the R8500 router and plugged in direct to CM1000 modem, I got around 500 - 650.


      I clearly see I have an issue between the CM1000 modem and the R8500 router, but Im trying to get the speeds right from the CM1000 first before I try and figure out where the slow down is on the router.

       

      I'm new to having gigabyte speed, signed up two days ago, so I just began troubleshooting the issue.

      • plemans's avatar
        plemans
        Guru - Experienced User
        Mar 28, 2020

        You're correct in that you want to get gigabit speeds to the modem first. Good call on that. 

        In terms of your powerlevels, you're way out of spec. Optimum power levels for downstream are -7dbmv to +7dbmv.  acceptable but not optimal is -10dbmv to +10dbmv.  Non of yours are within spec. 

        Is the modem right where to coax enters the home? if not, move it there without any splitters, amplifiers, attenuators and then rerun this. extended runs/amplifiers/attenuators/splitters can all reduce signal strength.  

        If you still have the same results after moving it or if you've already done that, you'll want your isp to check your line.