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Question

Two different SB6190's reboot themselves multiple times per day with the same log messages


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I’ve had a SB6190 that was working fine for more than a year. A few weeks ago, it started rebooting itself multiple times per day, but once it rebooted, it reconnected to Xfinity just fine. Unfortunately, it would just do it again in a few hours, and obviously, internet service is interrupted for about four minutes each time.

Xfinity sent a service tech, who checked and said there is nothing wrong with their cable. He said the SB6190 should be fully supported on the Xfinity network, and suggested I buy a new one. I did buy a new one, and it behaves exactly like the one that is more than a year old. It works fine, until it reboots itself, and it does it just a frequently as my original SB6190. 

What do I telll Xfinity, since it’s obviously their network? Two different SB6190s (both tested when plugged into the wall and also tested when plugged into a UPS/surge protector) are acting identically.  In addition, there seems to be two entries in the logs that correspond to the timing of the reboots:

“No Ranging Response received - T3 time-out”

followed by

“Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out”

This can’t be a coincidence. It’s there each time just when the modem reboots. What is going on? Is Xfinity telling my modem to reboot, or are they failing to respond correctly, so my modem reboots itself, or is it something else?

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It's unlikely that the issue is with the modem itself, as new modems will reboot on their own. There are many possibilities for the modem restarting, such as an incompatible speed plan or improper signal levels.

Could you please help us with your subscribed internet speed plan? 


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Hi,

Thanks for the reply. My plan with Xfinity is up to 300 mbps download (unspecified speed upload, but much less). My first SB6190 had no issues for over a year, and my plan has not changed. Given that my second SB6190 is behaving exactly like my first, I really think something has happened to the network in my neighborhood. I think my only option is to keep after Xfinity. Mostly I wanted to know what a T3 and T4 timeout was so I could speak inteligently with Xfinity. I actually found a page describing those timeouts, which I will leave here in case someone else with my problem finds this thread in the future: 

T3 timeout: A T3 timeout happens when your modem sends a "keep-alive" request (a ranging request) to the CMTS (Cable Modem Termination System) and does not get a timely response.

T4 timeout: A T4 timeout is much more serious. It happens when your modem loses communication with the CMTS for an extended period. Essentially, it stops hearing from the CMTS completely.

The page finishes with:

If you're encountering repeated T3 or T4 timeouts:

  • Check your coaxial cables, splitters, and connectors for damage or corrosion.

  • Check modem signal levels (especially upstream power levels — they should ideally be below 50 dBmV).

  • Contact your ISP with your modem logs (they'll recognize T3/T4 errors immediately) — they might need to fix a problem on their end or send a technician.

Thanks again for your response.

 


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It appears you are reviewing the event log messages. We apologize for any confusion, but these logs are related to your internet service provider and reflect details about your internet service.


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