Have seen many, many people on this forum ask about why they are getting the error "Started Unicast Maintenance Ranging - No Response received - T3 time·out" on their Motorola MB8600 modem log. However, I have seen no definitive answers as to what the error means and how to fix it (or get it fixed).
The error indicates that I have lost Internet connection. For the first few months, this message never occurred as a "critical" message on my log, now I am receiving it more and more frequently. Each time I receive this, I need to restart my cable modem. Now this ois occurring several times a day. Any ideas?
3-Critical R2.0 No Ranging Response received - T3 timeout:
Explanation. The cable modem has sent 16 Ranging Request (RNG-REQ) messages without receiving a Ranging Response (RNG-RSP) message in reply from the CMTS. The cable modem is therefore resetting its cable interface and restarting the registration process. This typically is caused by noise on the upstream that causes the loss of MAC-layer messages. Noise could also lower the signal-to-noise ratio (SNR) on the upstream to a point where the cable modem's power level is insufficient to transmit any messages. If the cable modem cannot raise its upstream transmit power level to a level that allows successful communication within the maximum timeout period, it resets its cable interface and restarts the registration process.
Recommended Action No action is needed if this is an occasional problem. Check the upstream transmit power for the cable modem to see if it is at or near the maximum allowable levels. Check the RF plant for cabling or connector issues that could generate sufficient noise to lose MAC-layer management messages.
What do the modem's signal stats look like ? Try getting them here http://192.168.100.1 or here http://10.0.0.1
Please post the *Downstream Power Level*, the *Upstream Power Level*, and the *SNR* (Signal to Noise Ratio) numbers.
Thank you for responding so quickly. This problem is occurring every few hours, so I would like to solve it. Have attached the Connection log as you requested.
(Of my 25 years+ of being Internet-connected, have never had a problem like this. I am mystified.)
The stats as read at the modem level at that moment in time were good but there are three additional signal stats which can't be read by the modem. They can only be read from their end by them polling the CMTS (Cable Modem Termination System) at the local headend facility.
They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.
You can call in and ask what these figures are. The Upstream Receive Power Level should fall within the range of -2dB to +2dB with 0dB being in the middle and perfect.
The Upstream SNR should be least 31dB, and the higher it is the better.
The ICFR should be no higher than 2 dB.
You could have an intermittent noise ingress issue in only the upstream channel(s) / return path only somewhere.
They will be able to see whether or not everything is in the green zone and also see a history plot for the modem.
Thanks again, EG, for your informative response. I will contact Comcast/Xfinity and request the items you listed. I will respond back on this Forum as to what I learn and accomplish towards retoring my service -- in order to leave a trail for those who have the same kind of situation.
Good luck ! Post back with the outcome.
I tightend up connection all the way to the pole, turned the modem of for 4 hours -- and voila. It.s been work for a week. Thanks
Thanks for posting back. Good luck with it !
This problem will return for you. It has been happening to me for years and they cannot, or will not, fix it. They likely know exactly why this is happening and it is likely something that requires a lot of money for them to replace shot lines in a large area, or fixing their tech equipment, etc. This is honestly the worst company I've ever known, and it's not even close.
Yes, the problem returns every few weeks, and then every few hours. So, I unplug my modem for 3-4 hours and plug it back in, and I get another few weeks. I hate "magic" like that, but am not sure Comcast could do better. Aaaargh.