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jzsmart3
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Saturday, December 27th, 2025 10:23 AM

Customer-owned DOCSIS 3.1 modem capped at 200 Mbps on a 1 Gig plan

Today I activated a customer-owned DOCSIS 3.1 modem, the Hitron CODA56, which is specifically recommended on Xfinity Device Info page for my service. The modem is online, but I’m capped at ~200 Mbps download. I’m on a 1 Gig plan.


Chat and IVR, which are not helpful, will NOT allow Agent. I need the modem reprovisioned and the correct bootfile pushed, as my new CODA56 has been provisioned to wrong 200 Mbps bootfile on 1G plan despite activation and repeated resets. Thanks.

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18 hours ago

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EG

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14 days ago

Concern moved here to the Customer Service help section for greater exposure to Comcast corporate employees (The Digital Care Team) for assistance.

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jzsmart3

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Figured out. Issue was related to prior pfSense QoS setting to fix Buffer Bloat. I have asked Gemini to summarize the issue and fix:

Technical Summary: Throughput Bottleneck Resolved

Subject: Resolution of 400 Mbps Speed Cap – Configuration Conflict on CPE

Issue Description: Following a hardware upgrade to a Hitron CODA56 (DOCSIS 3.1) and a transition to the Xfinity Gigabit Extra tier, the connection was consistently capped at approximately 400–420 Mbps Download and 40 Mbps Upload. Diagnostics were performed to determine if the bottleneck was physical (layer 1/2), ISP-provisioning related, or internal routing overhead.

Diagnostic Steps Taken:

  1. Interface Verification: Verified the WAN interface (Intel igb0) was negotiating at 1000baseT <full-duplex> with 0 input errors and 0 drops (netstat -i -d), ruling out physical cable or port negotiation issues between the 2.5G modem port and the 1G router port.

  2. Provisioning Check: Confirmed with Xfinity support that the correct Next-Gen Gigabit bootfile (d11_m_coda56_gennxgig_c01.cm) was pushed and active.

  3. Service Overhead: Temporarily disabled multiple OpenVPN instances to rule out CPU "context switching" bottlenecks on the router's i3 processor.

  4. QoS/Traffic Shaper Audit: Identified an active FQ_CoDEL Limiter within the pfSense firewall.

Root Cause: The bottleneck was a legacy Traffic Shaper (Limiter) configuration. The router was configured with a "Download Pipe" hard-coded to 500 Mbps and an "Upload Pipe" of 20 Mbps. These settings were originally implemented to mitigate "Bufferbloat" on a previous, slower service tier. Due to the computational overhead of the CoDel algorithm on a single CPU core, the 500 Mbps logical limit resulted in an effective real-world throughput of ~400 Mbps.

Resolution: The Download Limiter was updated to 950 Mbps (to match the physical overhead of the 1G Ethernet handoff) and the Upload Limiter was increased to 100 Mbps. Immediately following these changes, the system achieved a sustained throughput of 940+ Mbps Download and 115+ Mbps Upload, confirming that the Xfinity "Mid-Split" provisioning and the Hitron hardware are performing at peak specifications.

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14 days ago

XfinityThomasD

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14 days ago

 

jzsmart3 Thanks for creating a post. Have you also tried to run the internet troubleshooting diagnostics through the Xfinity app? I ask since it will automatically check and provision the equipment as well. Our team is of course here to help if needed as well. If you still need assistance, please send our team a direct message with your full name and address.

To send a Direct Message:

 

Ensure you are logged in

  • Click the "Direct Messaging" icon or https://forums.xfinity.com/direct-messaging
  • Click the "New message" (pencil and paper) icon
  • The "To:" line prompts you to "Type the name of a person". Instead, type "Xfinity Support" there.
    • As you are typing a drop-down list appears. Select "Xfinity Support" from that list.
    • An "Xfinity Support" graphic replaces the "To:" line.
  • Type your message in the text area near the bottom of the window
  • Press Enter to send it.

 

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jzsmart3

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Thank you for responding.  On the Android Xfinity app, under Services, Modem is listed as Online and Banner says "Download speeds up to 1 Gbps."  Under Troubleshoot, it currently shows Download speed of 481 -- should of course be something approaching 1G. This is similar to other tests on my Network.
Other option on Troubleshooting is just to Dump me out to Xfinity Chat Bot. I've already wasted a few hours on that, to no avail. The best understanding of the current situation appears to be from ChatCPT and Proplexity -- both indicate that this situation is Comcast faulty provisioning of the new "recommended" DOCSIS 3.1 modem, and that a HUMAN employee at Comcast must reprovision my new DOCSIS 3.1 modem and push the correct bootfile, so that I can get the promised 1G Download speed. 

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14 days ago

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user_yoi1xy

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18 hours ago

I’m literally having the same issue. Beeen dealing with Xfinity for 36 hours. 2 techs being sent out for no reason and still no solution. I’ve went as far as bought another brand new HITRON coda56 modem and also a netgear cm3000 modem and still having the same provisioning issues. Reps over the phone will do their basic diagnostic, hit a wall and then  say they need to send a tech, blaming it on a defective modem or coax cable. Both of The techs comes out and confirms it’s a software provision issue, cables and hardware are fine and tells me to call customer care. I’m in an endless loop going on3 days now.

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