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Frequent Internet Disconnects. Started Unicast Maintenance Ranging - No Response received - T3 time

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Frequent Internet Disconnects. Started Unicast Maintenance Ranging - No Response received - T3 time

As the title states, I am randomly losing internet connectivity rather frequently. Started 2-3 weeks ago. Multiple times per day, connectivity drops for approximately 2-10 minutes. During this time, internet connectivity to external websites drops first, followed by connectivity to the modem.

 

The modem is a Netgear C6250 (AC1600) modem, which is one of the xfinity approved modems with DOCSIS 3.0 for my internet package. Every time connectivity is lost, when I log into the modem and check the log, "Critical(3) Started Unicast Maintenance Ranging - No Response received - T3 time-out" is the most recent entry. The modem is connected to the coax outlet directly inside the house from where the coax from the pole enters the house. It is a direct connection, with no splitters, to the outside line.

 

In the process of troubleshooting, I have changed the cable, changed the modem, even asked for an Xfinity XFI (Nice new white modem) to see if this would solve the problem. I have eliminated and removed all other devices from my network and plugged my computer directly into the modem, and the problem still persists. Since COVID19, my wife and I have been working from home and this has been very annoying to keep getting dropped from meetings and calls, as well as teaching for my wife.

 

I will post the LOG as well as my Upstream and Downstream info.

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Re: Frequent Internet Disconnects. Started Unicast Maintenance Ranging - No Response received - T3 t

TimePriorityDescription
2020-10-18, 10:35:23Notice (6)Honoring MDD; IP provisioning mode = IPv6
2020-10-18, 10:35:17Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.0;CM-VER=3.0;
2020-10-18, 10:34:52Critical (3)No Ranging Response received - T3 time-out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.0;CM-VER=3.0;
2020-10-18, 10:34:21Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.1;CM-VER=3.0;
2020-10-18, 10:19:23Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.1;CM-VER=3.0;
2020-10-18, 10:06:51Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.1;CM-VER=3.0;
2020-10-18, 10:05:58Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.1;CM-VER=3.0;
2020-10-18, 10:05:54Critical (3)Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.1;CM-VER=3.0;
2020-10-18, 10:03:56Warning (5)MDD message timeout;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.1;CM-VER=3.0;
2020-10-18, 10:03:25Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.1;CM-VER=3.0;
2020-10-18, 10:03:25Warning (5)MDD message timeout;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.1;CM-VER=3.0;
2020-10-18, 10:01:51Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.1;CM-VER=3.0;
2020-10-18, 10:00:59Notice (6)Honoring MDD; IP provisioning mode = IPv6
2020-10-18, 10:00:53Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.0;CM-VER=3.0;
2020-10-18, 10:00:15Critical (3)No Ranging Response received - T3 time-out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.0;CM-VER=3.0;
2020-10-18, 10:00:03Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-10-18, 10:00:01Critical (3)No UCDs Received - Timeout;;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-10-18, 09:59:51Warning (5)Lost MDD Timeout;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-10-18, 09:59:40Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.0;CM-VER=3.0;
2020-10-18, 09:59:38Critical (3)Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.0;CM-VER=3.0;
2020-10-18, 09:59:15Critical (3)No Ranging Response received - T3 time-out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.0;CM-VER=3.0;
2020-10-18, 09:59:09Critical (3)SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2020-10-18, 09:59:08Critical (3)Unicast Ranging Received Abort Response - Re-initializing MAC;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.0;CM-VER=3.0;
2020-10-18, 09:58:34Critical (3)No Ranging Response received - T3 time-out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.0;CM-VER=3.0;
2020-10-18, 09:57:57Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.1;CM-VER=3.0;
2020-10-18, 09:42:53Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.1;CM-VER=3.0;
2020-10-18, 08:52:50Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.1;CM-VER=3.0;
2020-10-18, 08:51:52Notice (6)Honoring MDD; IP provisioning mode = IPv6
2020-10-18, 08:51:47Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.0;CM-VER=3.0;
2020-10-18, 08:51:12Critical (3)No Ranging Response received - T3 time-out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.0;CM-VER=3.0;
2020-10-18, 08:50:47Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.1;CM-VER=3.0;
2020-10-18, 08:48:17Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.1;CM-VER=3.0;
2020-10-18, 05:31:44Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.1;CM-VER=3.0;
2020-10-18, 05:30:54Notice (6)Honoring MDD; IP provisioning mode = IPv6
2020-10-18, 05:30:48Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.0;CM-VER=3.0;
2020-10-18, 05:30:23Critical (3)No Ranging Response received - T3 time-out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.0;CM-VER=3.0;
2020-10-18, 05:30:00Critical (3)Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.1;CM-VER=3.0;
2020-10-18, 05:27:35Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.1;CM-VER=3.0;
2020-10-18, 03:56:53Notice (6)Honoring MDD; IP provisioning mode = IPv6
2020-10-18, 03:56:47Critical (3)Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=b0:b9:8a:0f:29:d0;CMTS-MAC=00:9e:1e:58:88:ee;CM-QOS=1.0;CM-VER=3.0;
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Re: Frequent Internet Disconnects. Started Unicast Maintenance Ranging - No Response received - T3 t

Startup Procedure
ProcedureStatusComment
Acquire Downstream Channel627000000 HzLocked
Connectivity StateOKOperational
Boot StateOKOperational
SecurityEnabledBPI+
IP Provisioning ModeHonor MDDhonorMdd(4)
 
Downstream Bonded Channels
ChannelLock StatusModulationChannel IDFrequencyPowerSNRCorrectablesUncorrectables
1LockedQAM25633627000000 Hz-11 dBmV36.5 dB23781442
2LockedQAM25625579000000 Hz-10.6 dBmV38.3 dB16861278
3LockedQAM25626585000000 Hz-10.7 dBmV38.5 dB24291648
4LockedQAM25627591000000 Hz-10.6 dBmV38.6 dB24391210
5LockedQAM25628597000000 Hz-10.2 dBmV38.9 dB21701641
6LockedQAM25629603000000 Hz-9.9 dBmV39 dB18391339
7LockedQAM25630609000000 Hz-10.4 dBmV38.7 dB20121134
8LockedQAM25631615000000 Hz-10.2 dBmV38.8 dB2244923
9LockedQAM25632621000000 Hz-10.6 dBmV38.1 dB2290953
10LockedQAM25634633000000 Hz-10.7 dBmV34.4 dB21071200
11LockedQAM25635639000000 Hz-11.1 dBmV35.4 dB19441110
12LockedQAM25636645000000 Hz-11.2 dBmV37.9 dB18971160
13LockedQAM25637651000000 Hz-11.9 dBmV37.3 dB19511093
14LockedQAM25638657000000 Hz-11.9 dBmV37.4 dB1419852
15LockedQAM25639663000000 Hz-11.8 dBmV37.4 dB1302929
16LockedQAM25640669000000 Hz-12.1 dBmV37.1 dB16101100
 
Upstream Bonded Channels
ChannelLock StatusUS Channel TypeChannel IDSymbol RateFrequencyPower
1LockedATDMA75120 Ksym/sec22800000 Hz45.5 dBmV
2LockedATDMA55120 Ksym/sec35600000 Hz47 dBmV
3LockedATDMA65120 Ksym/sec29200000 Hz47.5 dBmV
4LockedATDMA85120 Ksym/sec16400000 Hz45.5 dBmV
 
 
 
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Re: Frequent Internet Disconnects. Started Unicast Maintenance Ranging - No Response received - T3 t

The dowstream power is too low and it may be intermittently fluctuating even lower out of spec. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In a self troubleshooting effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage types like GE, RadioShack, RCA, Philips, Leviton, Magnavox, and Rocketfish from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two way splitter connected directly off of the drop from the street/pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed, and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.



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