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CT - Started Unicast Maintenance Ranging - No Response received - T3 time-out;

I have been experiencing the following modem error - as reported in the log at - for about two months:

Started Unicast Maintenance Ranging - No Response received - T3 time-out;

The visible symptom of the error is loss of connectivity for about a minute as the modem struggles to regain the internet connection. This is despite a very strong, clean signal being measured from the pole and throughout the house by four technicians.

This error obviously duplicates those being reported here by other customers widely spread out across the US, so I wanted to document the troubleshooting steps and technician interventions that have taken place to date - in the hope of moving the issue forward.

Bottom line: After two months of extensive investigation, there has been no change and no positive diagnosis. I still experience T3 disconnects daily. This issue is with Cox, and not with anything between the street pole and my computer. 

For reference, I have experience this error with three modems: Motorola 6180, 6121, and Cisco 3010

Troubleshooting and technician steps, in order:

  • Tech #1 reads signals at the box on the house, says they are fine, replaces in-home 3-way spitter in the basement since existing one was "old." No effect on T3 disconnects.
  • Customer bypasses all house wiring and connects modem by short length of new coaxial cable directly to the box on the house. No effect on T3 disconnects.
  • Customer purchases TWO new, Cox-approved modems and connects each one separately to the box on the house. No effect on the T3 disconnects - timeouts observed on both new modems.
  • Customer tries running system without Wi-Fi router - no effect.
  • Tech #2 listens to me recount the troubleshooting steps above, takes a picture of the modem's log screen to send to regional/area supervisor, etc - no additional response, no effect on T3 timouts.
  • Tech #3 again reads signals at the box on the house and assures me they are strong (which I know they are.) Tech installs a frequency "trap" on one modem to limit any possible signal interference. No effect - T3 errors still being observed.
  • Customer escalates issue with Cox - senior field line technician called to the house. Line tech replaces box on side of house, line from pole to box, and short run of interior cable from box to modem. Tech extensively tests incoming signal as well as in-house wiring for interference, and notes that all signals in and  out of house are remarkably clean and strong. T3 timeout error continue the same day. 
At this point, there is nothing more to be done inside the house, as the senior tech acknowledged. The issue now enters the realm of mysterious, hard-to-track problem that will likely never be addressed. 
Thoughts, anyone?

  • Could be random fluctuating power levels on the cable either from the street box to your house or somewhere in your house, Only way to explain this error constantly happening, If its random it more then likely is normal when they check the levels so they dont notice it, Because if you have went through numerous modems and still get this issue its def something Line/System related for Cox to fix.

  • You should log into your modem and take Screen shots of the power levels at random times of the day, This way you can post them here if they appear different from each other, Will help a cox tech figure out the problem!

  • Same situation here.  The intermittent signal loss has been ongoing for approximately 2 months now.  Cox tech support only confirms signal strength to house and confidently ensures me it has to do with my equipment.  I've swapped out splitters, bypassed router, etc.  They sent a tech out to my house who arrived late.  By the time he arrived, I had already left to be at another appointment and he ended up speaking with my wife, who had no idea of the problem.  The tech cycled my coax cable, told her the problem was fixed and left...then charged me $45.  Insane.  Please let me know if anyone is able to find a fix.

  • Just to update this post: I have now taken the additional step of purchasing a decent battery backup unit with power-conditioner capability, just to eliminate the possibility that fluctuating power levels could be causing the issue. Predictably, the T3 disconnects continued just the same, even with modem and router plugged into battery backup. (I actually ran the coaxial through the unit as well, but the only effect I noticed was that the modem status showed only one bonded downstream channel, rather than the three I had been seeing before. Disconnecting the coax passthrough in the battery backup box restored the three bonded channels. The T3 timeouts occurred whether I had the coax running through the battery box or not.)

    I can't come to any conclusion here other than the problem is with Cox's line outside my house. As a reminder:

    I've run this setup with multiple modems, no splitters, directly connected to the NEW box with NEW cable drop from the pole, and now with power conditioner installed - all with no effect on T3 timeouts.

    I'm not sure where to go from here.

  • Check your private messages.  Could you reply to mine with your account details please?