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user_9yg0rz
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3 Messages

09/06/2026 1:34 AM

xfinity support

I’m having a persistent latency/jitter issue on my 1 Gig Xfinity connection. I’ve already completed multiple modem resets and reprovisioning with support, and the issue remains.

My wired local connection is clean:

  • 0% packet loss to the XB7 gateway
  • About 0–2 ms gateway latency
  • 2.5 Gbps Ethernet link
  • Around 1.0–1.1 Gbps download and 110–120 Mbps upload
  • Idle internet tests show 0% packet loss

The problem happens under download load. Waveform repeatedly shows about +55 to +65 ms of added download latency, while upload latency stays around +5 to +6 ms. I’ve received C and B bufferbloat grades even though the LAN side stays clean. I’ve already ruled out the Ethernet cable, NIC, driver, local gateway connection, and basic reset troubleshooting.

Please escalate this for investigation of downstream signal quality, node utilization/congestion, ingress/noise, CMTS performance, and the outside line/tap. I already have an escalation ticket and would like to avoid repeating modem resets that have not fixed the issue.

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11 days ago

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XfinityThomasA

Official Employee

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3.9K Messages

18 days ago

 

user_9yg0rz - Thank you for your feedback and for joining us here on the Forums. We'd be happy to help troubleshoot this with you.

To start, you mentioned your wired local connection is clean and the problem happens under download load. To confirm, does this issue occur when you're using a wired connection, WiFi, or both? Are you having trouble downloading a specific file, application, or update?

There are a few things that may help improve download performance. If possible, close any data-intensive applications that may be running in the background, such as cloud backup services (OneDrive or Google Drive), video streaming platforms, or other game launchers and download managers. If you're connected through a VPN, try temporarily disabling it during the download, as VPNs can add extra encryption and routing that may impact speeds.

You may also want to temporarily pause real-time web or file scanning in your antivirus software while the download is in progress, then re-enable it immediately afterward. This can sometimes help if the security software is slowing the download process.

Please let us know what you're unable to download and we'll be happy to continue troubleshooting with you.

 

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user_9yg0rz

Visitor

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3 Messages

Thanks. I want to clarify one point from my original post. Further testing shows this is broader than the download-latency result I originally reported. I replaced the Xfinity gateway today, and the issue remains. During the events, my local gateway at 10.0.0.1 stays stable at about 1–3 ms with 0% loss, while the first Xfinity hop and external targets sometimes show higher latency or missed replies. Please note, I’m testing over wired Ethernet with no VPN or heavy background traffic.

Since resets, reprovisioning, and now a gateway replacement have not fixed it, can your team please escalate to review my site's history?

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15 days ago

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XfinityDena

Official Employee

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4.7K Messages

@user_9yg0rz

 

I want to make sure we are respecting your time and not repeat the steps you have taken previously. What troubleshooting steps have you taken? 

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please mark as Best Answer.tick

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13 days ago

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user_9yg0rz

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Thanks for taking on this issue @XfinityDena, I appreciate you trying not to repeat steps I’ve already done.

Xfinity already upgraded me to 1000 down and 100 up, replaced my XB7 with an XB8, restarted and reprovisioned the gateway, and I’ve tested over wired Ethernet with different Ethernet adapters and cables. I’m the main Internet user, there’s no heavy traffic when the issue happens, and I’ve tested with VPN and background apps off.

My local connection to the XB8 stays stable at about 0–3 ms with 0% packet loss, even when the Internet-side jitter happens. I’ve also run repeated latency, packet-loss, and bufferbloat tests, changed DNS, tested NIC settings, and captured network traces during the jitter events.

My speeds are now close to the full plan, around 1 Gbps down and 110–120 Mbps up. The main issue left is intermittent upload latency/jitter.

The current DOCSIS levels also look normal, with all channels locked and good signal levels. Since the issue continued with both the XB7 and XB8, could you please check the Comcast-side history for upstream errors, T3/T4 timeouts, OFDMA issues, noise, packet loss, or node/CMTS congestion?

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11 days ago

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XfinityKei

Official Employee

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2.8K Messages

@user_9yg0rz Thanks for sharing those details with us. Can you please direct message me your first and last name along with your full service address so I can assist you further?
To do so, click on the chat icon located at the top right of this forum's page.
Here are the detailed steps to direct message us:
• Click "Sign In" if necessary
• Click the "Direct Message” icon (upper right corner of this page)
• Click the "Start new conversation" (pencil and paper) icon
• Type "Xfinity Support" in the "to" line and select "Xfinity Support" from the drop-down list
• Type your message in the text area near the bottom of the window
• Press Enter to send your message

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please mark as Best Answer.tick

Like

Reply

11 days ago

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