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Sporadic download speeds, consistent upload speeds

abaldanabaldan Posts: 3
in Connectivity May 12, 2018

Your location. city, state, zip. Single or multi family complex.

Akron, OH 44321. Apartment building (around 20 units)


Services you get from TWC



Make and model of modem

Arris SURFboard SB6121


Make and model of router(s)

TP Link Archer C7


Firmware level in modem



Modem status



Purchased speeds

100 Mbps down / 10 Mbps up



Download speed often drops to less than 10 Mbps and as low as 0.2 Mbps. Upload speed is very consistent near 10 Mbps as purchased. Rebooting the modem typically restores download speed to near 100 Mbps but not always.


Modem signal and logs

2018-05-12 14_15_36-

2018-05-12 14_16_52-



RG6 cable direct from wall to modem



Wall -> RG6 cable -> SB6121 -> cat5 cable -> TP Link TL-SG1005D switch -> cat5 cable -> PC


Recent changes

None to my knowledge


 Pathping to rr.com

2018-05-12 14_31_59-Administrator_ Command Prompt.png


Speed problems during all usages (web browsing, streaming, gaming)


Background apps:





  • karlbeckmankarlbeckman Posts: 2,208 ✭✭✭✭
    May 12, 2018

    This one is very easy to resolve. Spectrum requires 8 DS channels to provide 100 Mbps internet service.  Your existing SB6121 modem only has four.  thus it will not operate above 60 Mbps on the TWC/Spctrum network.  You need to upgrade to a new DOCSIS3 modem with at  least 8 downlink channels.   You can either rent one from Spectrum or purchase one that is on their list of approved models for your desired future speed tier.  

    I would recommend buying a 16 channel modem that is approved for one or more speed tiers higher than you need today, but DO NOT buy a 3-in-one modem + router + WiFi combined unit.  You want to have the router and WiFi in separate units so you can position the WiFi to get the best coverage around your home.

  • abaldanabaldan Posts: 3
    May 12, 2018

    Is the modem still the issue if there are many instances where I am getting my subscribed speeds of 100 Mbps down? This is not a case where I am never getting the speed I am paying for, just very inconsistently. My speed does not max out at 60 Mbps.

  • karlbeckmankarlbeckman Posts: 2,208 ✭✭✭✭
    May 14, 2018

    When your modem is properly set up and programmed for the 60 Mbps plan, it will receive brief downloads up to about 78 Mbps peak.  It won't pass Speedtest at 100 though, and it doesn't work with the 16 DS channel plans now being installed across northeast Ohio.  60 Mbps is the fastest tier that TWC or Spectrum will program into the SB6121.  This I know from experience - I used to have a SB6121. 

    But here's something far more serious:  Your system is also missing the router that goes between the modem LAN port and the TP Link TL-SG1005D switch.  The router is required if you have more than one computing device on your home's private LAN.  Most also include WiFi radios so you can avoid using Ethernet cabling to all devices.

  • abaldanabaldan Posts: 3
    May 14, 2018

    Thanks for clarifying. I've ordered a TP-Link TC-7620 as an upgrade.


    Here are the devices within the signal path:

    - Modem

    - TL-SG1005D

         - - PC

         - - Stereo receiver

         - - BD player

         - - Printer

         - - Fire TV (faster on ethernet than wifi)

         - - Wifi Router

              - - Laptop

              - - Smartphones


    My old setup had the ethernet devices pass through the router. Which is the better setup?

  • karlbeckmankarlbeckman Posts: 2,208 ✭✭✭✭
    May 14, 2018

    All wired devices need to somehow go through your router.  Otherwise only one device at a time can connect, using the single internet address for your account.  The WiFi radios are already connected to the router internally, so that covers your smartphones and Fire stick. However, CAT-5e cable is good up to 1 Gigabit and it will always be faster than WiFi for your video streaming devices.  

    You can plug the ethernet LAN switch into one of the router's LAN ports, to have four additional ports for your wired connections -it's going to work like a power outlet strip. 


    Last, for a more useful tracert test, use google.com as your target rather than a Roadrunner Email server.

This discussion has been closed.