cm600 won't negotiate 800down/100up

hi,

gear: cm600, firmware V1.01.22, latest approved by xfinity.

router is ubiquiti ER-X (1gig cable aggregate).

xfinity super fast, 800down/100up, purchased plan. we just went from a triple play to a double play so i'm paying attention to the plan and what i'm actually getting.

i've been through 2 rounds of xfinity cs. on the wired connection my system speed tests at 300-500 down, 20-25up on a newer macbook pro 1gig capable.

they claim the provisioning went normally and i'm all 'green' at their end. yet i'm not getting what i paid for. they're trying to point the finger at at netgear and the cm600. so here i am asking for community help.

on the cable modem signal levels on the downstream channels are fine, 3.5dBmV. only 4 of 8 upstream channels are bonded. those are also at 3.5dBmV.

is this a known issue? is xfinity just pointing a finger? i did get them to send a tech to check the lines outside the house because i didn't receive the text message after the first round of trouble shooting was complete, the 1 hour long testing.

i am tempted to buy the cm700 to show them the issue is with them. i do not want nor should i have to use their modem, and pay for it.

other thoughts? i've attached screenshots of the the cable modem diagnostics.

thanks,

jeff

20 Replies

plemans
Guru - Experienced User
Oct 09, 2023
I'd be betting on it being that modem. Xfinity just bumped up their upload speeds but only on midsplit/highsplit devices.

The cm600 (and the cm700) won't cut it currently.

knowledgebase/next-generation-internet - Comcast_Xfinity (reddit.com)

If you're shopping for a new modem, I'd look for at least a docsis 3.1 device.
- greeno
  Apprentice
  Oct 09, 2023
  thank you for that link. the modem is 1gig capable and docsis 3.0 (3.1 isn't that different). i see a cm1100 for a pretty good price on amazon. i'll buy it and try it. thanks for the reply.
  jeff
  - plemans
    Guru - Experienced User
    Oct 09, 2023
    the cm600 is only a 24x8 docsis 3.0 device. While the specs say up to 1 gig, xfinity doesn't certify it to those speeds.
    
    Its only the docsis 3.1 devices they certify up to 1 gig. Even the cm700, which is a 32x8 modem, isn't gigabit certified. It can hit 900mbps but itsn't certified for it through xifnity.
    
    A CM1100 is a good option. I've got one and its a solid device

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cm600 won't negotiate 800down/100up