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Question

ISP says they are pushing DOCSIS 3.1, Modem Says Differently, Arris Agrees with ISP.


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Introduction

For starters, I live in an apartment complex that only has one ISP available (Cox). I purchased a SB8200 and a TP-Link ARCHER AX20 for the upgrade of service I was getting through cox. 

Number 1 Red Flag: The mobile app (SURFBoard Central).. I mean what a waste of time. This app serves no purpose other than showing you a email link to download a desktop app named “Fing” like who cares lol.

Number 2 Red Flag: Upon reading the user manual, you can see the LED status screens on the front:

USER MANUAL​​​​

The plan for my internet is set to utilize DOCSIS 3.1, however the LEDs on the front all line up for 3.0.

 

Troubleshooting:

  • Obviously, restarted the modem
  • Checked connections
  • Use proper cables
  • Interface Status Screen
    • Side note: what a pain it is to get to this screen.

Upon finally checking the status screen, I am met with these numbers:

DOWNSTREAM CHANNEL STATUS

I do not know if these numbers are correct, but one other note I had was on the “Product Information” screen, it listed one line as DOCSIS 3.1 and the other line said 3.0. 

 

I need to verify if my modem is receiving and running on DOCSIS 3.1, but how can i do that when the LED on the modem says no, while the manufacturer and the ISP both agree that it is running on DOCSIS 3.1!!!

 

Please help. 

plemans
Juggernaut
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  • Juggernaut
  • March 20, 2025

why does it need to be “docsis 3.1”? 

Is it getting the speeds you pay for? 

many isp’s (the tier 1 techs won’t know) still use the docsis 3.0 connections for lower tiers or to hit diffent speeds. 

are you not getting your speeds? 

Having issues?


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  • The Many
  • March 20, 2025

I want to be on DOCSIS 3.1 because it provides better performance, lower latency, and improved stability, even if my speeds seem fine (¾ of what I pay for). My issue isn’t just about hitting my plan’s speeds—it’s that my modem’s status indicators don’t match what my ISP claims.

 

According to both the manufacturer and my ISP, my service should be running on DOCSIS 3.1, yet my modem’s LED status and interface screen suggest it’s still on 3.0. I’ve already gone through all the basic troubleshooting steps—checking connections, using proper cables, restarting the modem, and verifying settings—yet the inconsistency remains.

 

I’m trying to figure out if my ISP hasn’t fully provisioned my modem for DOCSIS 3.1 or if something else is preventing the switch. Has anyone dealt with this before, and how did you get your ISP/Arris to acknowledge and resolve it?


plemans
Juggernaut
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  • Juggernaut
  • March 20, 2025

A couple things. 

  1. 3.0 to 3.1 didn’t change latency unless you in one of the xfinity LLD (low latency docsis) trial areas. 
  2. your power levels are all over the place. They should be within 3.5dbmv of each other. Yours is from -1 to 11 dbmv. Way out of spec. And thats not even seeing your logs. 
  3. 3.1 added ofdma channels which are the higher speeds/spec channels. the screensnips you took aren’t of the ofdma chanels. So it doesn’t help a whole lot other than tell me that your line has issues and you’re not aware of what 3.1 is other than a value that you want. 

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  • The Many
  • March 20, 2025

1. I understand that transitioning from DOCSIS 3.0 to 3.1 does not necessarily reduce latency unless you are located in a low-latency trial area.

 

2. The power levels ranging from -1 to 11 dBmV are quite wide. What practical measures can I take within an apartment complex to enhance my internet connection?

 

3. I am aware that OFDMA channels are a crucial component of 3.1. The screenshots I shared only provide basic downstream statistics, not the OFDMA-specific details (check bottom of first photo).

 

Look, I’m relatively new to this, and it’s my first time owning an ISP account, third-party network devices, and so on.

 

I pay for 1000 Mbps, but I don’t have that many devices, so I should theoretically get as close to those speeds as possible. However, the fastest speed test results (Ookla, Fast.com, Cloudflare) have only reached just over 500 Mbps. 

 

I hope you can understand my frustration. 


plemans
Juggernaut
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  • Juggernaut
  • March 20, 2025
  1. you should reach 940mbps with that device. But thats directly through the modem. Some routers will decrease throughput depending on what data inspection (traffic monitoring, parental controls, etc) they’re doing. Test your speed directly off the modem. 
  2. Your power values are way out of spec. About all you can do from an end-user is remove everything from the coax and directly connect the modem to where the coax comes into the apartment. If you’re still getting those values, your ISP needs to check the line and connection before your apartment. 

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  • The Many
  • March 20, 2025

Figured as much. Thanks. 


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  • Rockstar!
  • March 24, 2025

@CASEYLP Go to the Product Information page on the SB8200, Standard Specification Complaint will tell you if the modem is in D3.1 mode.  I got the screenshot from their serial number lookup FAQ.  I recall seeing 3.1 on my modem when I had Xfinity service.

 

https://arris.my.salesforce-sites.com/consumers/articles/General_FAQs/SB8200-Locating-the-Serial-Number

 


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