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WingZero's avatar
WingZero
New Contributor II
2 years ago

Docsis 3.1 SB8200- getting 300mbps speed only. Have gigablast plan

I currently have a gigablast plan and I am only getting 300mbps on all speed test. I have rebooted the modem and switch and swapped out the coax cable from the cable to the wall and the LAN cables as well with no speed improvement. I logged into the modem and the event page is littered with "Dynamic range window violation". Not so sure if the SNR values are within range. I reached out to cox support over the phone and both times said there's nothing wrong but I am not getting the speed I am paying for.

RESOLVE:

bypassed the router and directly with the modem I am getting the whole gig speed. odd considering the router has gig ports but I factory reset the router and now I am back to my expected rate speed. thanks for the support.

https://imgur.com/gw8UsIB

https://imgur.com/PPyxwg7

https://imgur.com/ZuqIyF6

https://imgur.com/kno8o8v

  • WingZero's avatar
    WingZero
    New Contributor II
    2 years ago

    bypassed the router and directly with the modem I am getting the whole gig speed. odd considering the router has gig ports but I factory reset the router and now I am back to my expected rate speed. thanks for the support.

    • Darkatt's avatar
      Darkatt
      Honored Contributor
      2 years ago

      Great! Glad to hear it's all 100%. Believe it or not, I have found that 9 out of 10 times, or MORE even, the router is causing an issue. Don't know why, but slow downs, WiFi issues, strange drops, and many times, a factory reset squares it away. 

      • WiderMouthOpen's avatar
        WiderMouthOpen
        Esteemed Contributor
        2 years ago

        A factory reset is good troubleshooting but if the issue comes back you are going to have to do some deep diving into why the problem happened. Did you change any settings from default when you first installed the router? Did the speed go back down when a certain device reconnected to the network?

  • WiderMouthOpen's avatar
    WiderMouthOpen
    Esteemed Contributor
    2 years ago

    What model router and switch do you have? Have you tested direct to the modem with ethernet? Your signal levels are great and you have 2 downstream OFDM channels so congestion should be less of a issue.

    • WingZero's avatar
      WingZero
      New Contributor II
      2 years ago

      I have a RT-AC5300. I did connect my pc directly to the modem but it didnt obtain an ip address.

      • WiderMouthOpen's avatar
        WiderMouthOpen
        Esteemed Contributor
        2 years ago

        You have to power cycle the modem each time you change what it is plugged into(PC or router). If connecting to the modem is fast but through the router is limited to 300Mbps, the first thing I would do is check QoS and NAT acceleration. Looks like the router itself bottlenecks around 791Mbps as per here.

  • Darkatt's avatar
    Darkatt
    Honored Contributor
    2 years ago

    try connecting your computer direct to modem with a good cat5e ethernet cable, reboot the modem, and test, see what the speeds look like with the router bypassed. Many routers slow things down, a LOT. I direct connection will give us a better look see.