Visitor
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1 Message
Severe Speed Degradation - T3 Timeout Errors - Need Technician Dispatch
Dear Xfinity/Comcast Support Team,
I am experiencing severe internet speed degradation. After extensive troubleshooting on my end, the following issues remain unresolved and are beyond the scope of router-level software fixes. I am requesting your direct intervention.
Modem: Motorola MB8600 (DOCSIS 3.1)
Background - Diagnostics Already Performed:
- Verified all Ethernet connections are gigabit-capable (CAT6 cables, gigabit NIC, gigabit router ports)
- Confirmed router LAN/WAN negotiation at 1.0 Gbps full duplex
- Disabled QoS/bandwidth control and parental controls on the router
- Changed DNS servers to Google DNS (8.8.8.8 / 8.8.4.4)
- Rebooted and renewed WAN lease multiple times
- Ran speed tests on Speedtest.net and Fast.com with consistently poor results (6-46 Mbps)
- Found numerous T3 timeout errors in the modem SNMP event log, indicating signal-level issues between my modem and the CMTS
Action Items Requiring ISP Support:
1. Check Coaxial Cable Connections - Ensure the coaxial cable from the wall outlet to the modem is securely tightened, undamaged, and not excessively bent.
2. Remove Extra Signal Splitters - If there are any splitters on the coaxial line, please test with a direct connection to rule out signal loss.
3. Line and CMTS Inspection (T3 Timeout Errors) - T3 timeout errors typically require an ISP technician to inspect the line and CMTS-side configuration. Please:
- Check and refresh my modem provisioning file
- Confirm whether my subscribed plan speed is gigabit
- Check if the CMTS node in my area has congestion or faults
4. Confirm My Xfinity Plan - Current measured speeds (15-46 Mbps) may reflect the actual subscribed plan speed rather than a gigabit plan. Please verify my account and confirm the subscribed tier.
5. Dispatch a Technician - If remote troubleshooting cannot resolve the T3 timeout errors and speed issues, please schedule an on-site technician visit to inspect the coaxial line, connectors, and signal levels at my address.
I can provide my account details and address via private message. Thank you for your prompt attention.
BruceW
Gold Problem Solver
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27.4K Messages
1 month ago
"ModMail" is the private message facility used on the Reddit web site. Here in the Xfinity Forums, the equivalent is Direct Messaging. Once again, an employee has posted incorrect instructions.
To send the requested information in a private Direct Message ("DM") to Xfinity Support from any forums.xfinity.com page:
• Click "Sign In" if that prompt is visible
• Click the "Direct Messaging" icon above-right
• On the DM page click the "New message" (pencil and paper) icon
• The "To:" line prompts you to "Type the name of a person" but don't do that. It won't work.
Instead, type Xfinity Support there. As you are typing a drop-down list appears.
• Select "Xfinity Support" from the list. An "Xfinity Support" graphic replaces the "To:" line.
• Type your message in the text area near the bottom of the window
• Press Enter or tap the > icon to send it
See https://forums.xfinity.com/conversations/email/cant-create-a-new-email-address/605e52b726aa974d63032d02?commentId=606107ea738c7f46a02b830e for an example.
Regrettably the "pencil and paper" icon is a pale grey that is active even though it does not look active. Go ahead and select it. But if a red circle-slash appears when you try to select the icon it means that DMs are disabled in your user Profile. To enable them go to your Profile Settings, clear the "Opt Out from Direct Messaging" checkbox, click Save, and try again.
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