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WorkingAtHome12's avatar
WorkingAtHome12
New Contributor II
5 years ago

T3 timeouts and low upstream power levels

My internet service experiences 2-60 disconnects a week since April 2019. Fixes have been made with varying results. Currently I am experiencing around 6 disconnects a week. I work at home and need a reliable internet connection. Any assistance admins can provide is greatly appreciated.

I believe the current disconnects are caused by a "mainline" issue. The negotiated cable modem upstream channel power to the CMTS is very low at 29-31 dBmV. I believe I am at the end of the line, close to an amplifier. I believe this is contributing to T3 timeouts. My downstream channel power levels are mostly fine (see note at bottom of post). My neighbors are also complaining of internet disconnects.

The last Cox technician to visit told me the lines are fine, and the issue is either the cable modem or the mainline. I replaced the cable modem that night and I'm still seeing T3 timeouts (though less). Can an admin please increase the cable modem upstream power levels or investigate further?

Below is a summary of recent actions/work:

All splitters have been removed between the underground cable coming to my house and the cable modem. We do not have cable TV.
All coaxial cable between the underground cable connection and the cable modem has been replaced with high quality cable.
Multiple technician have been to the house and detected no line issues using high quality meters. They have tested at the "tap", at the "bump", and at the cable modem.
3 different cable modems have had consistent T3 timeouts. An old Arris, a Motorola MB7621 (purchased in May), and a new Arris SB8200 (purchased one week ago and current modem).
The underground coaxial cable coming to my house was replaced at some point (4-18 years) before I purchased the house.

Also perhaps of concern, the variance of power between download channels seem much higher than typical. One channel in particular (159) is 15 dBmV stronger than the lowest channel power. That channel (159) also have a high number of correctable errors.

Again, any assistance from admins is greatly appreciated.

Below is the current cable modem's spectral analysis and error logs:

Downstream Bonded Channels
Channel ID Lock Status Modulation Frequency Power SNR/MER Corrected Uncorrectables
3 Locked QAM256 687000000 Hz -3.2 dBmV 40.6 dB 5 0
1 Locked QAM256 675000000 Hz -3.1 dBmV 39.6 dB 1 0
2 Locked QAM256 681000000 Hz -3.4 dBmV 40.5 dB 2 0
4 Locked QAM256 693000000 Hz -3.5 dBmV 40.5 dB 0 0
9 Locked QAM256 723000000 Hz -3.5 dBmV 40.5 dB 1 0
10 Locked QAM256 729000000 Hz -3.3 dBmV 40.7 dB 1 0
11 Locked QAM256 735000000 Hz -3.2 dBmV 40.7 dB 0 0
12 Locked QAM256 741000000 Hz -3.1 dBmV 40.8 dB 0 0
17 Locked QAM256 771000000 Hz -3.9 dBmV 40.3 dB 0 0
18 Locked QAM256 777000000 Hz -4.0 dBmV 40.2 dB 2 0
19 Locked QAM256 783000000 Hz -4.1 dBmV 40.3 dB 0 0
20 Locked QAM256 789000000 Hz -4.2 dBmV 40.1 dB 4 0
21 Locked QAM256 795000000 Hz -4.9 dBmV 39.7 dB 4 0
22 Locked QAM256 801000000 Hz -4.8 dBmV 39.7 dB 2 0
25 Locked QAM256 819000000 Hz -5.0 dBmV 39.6 dB 4 0
26 Locked QAM256 825000000 Hz -5.5 dBmV 39.3 dB 7 0
27 Locked QAM256 831000000 Hz -5.8 dBmV 39.3 dB 10 0
28 Locked QAM256 837000000 Hz -5.9 dBmV 39.0 dB 5 0
29 Locked QAM256 843000000 Hz -6.4 dBmV 38.7 dB 10 0
30 Locked QAM256 849000000 Hz -6.4 dBmV 38.7 dB 12 0
33 Locked QAM256 345000000 Hz 1.4 dBmV 42.1 dB 0 0
34 Locked QAM256 351000000 Hz 1.5 dBmV 42.6 dB 0 0
35 Locked QAM256 357000000 Hz 1.5 dBmV 42.6 dB 0 0
36 Locked QAM256 363000000 Hz 1.6 dBmV 42.7 dB 0 0
37 Locked QAM256 369000000 Hz 1.4 dBmV 42.7 dB 0 0
38 Locked QAM256 375000000 Hz 1.4 dBmV 42.6 dB 0 0
41 Locked QAM256 393000000 Hz 1.0 dBmV 42.5 dB 0 0
42 Locked QAM256 399000000 Hz 1.2 dBmV 42.5 dB 0 0
43 Locked QAM256 405000000 Hz 0.7 dBmV 42.3 dB 0 0
44 Locked QAM256 411000000 Hz 1.0 dBmV 42.5 dB 0 0
45 Locked QAM256 417000000 Hz 0.8 dBmV 42.5 dB 0 0
46 Locked QAM256 423000000 Hz 0.9 dBmV 42.4 dB 0 0
159 Locked Other 288000000 Hz 6.9 dBmV 43.5 dB 574403553 0

Upstream Bonded Channels
Channel Channel ID Lock Status US Channel Type Frequency Width Power
1 3 Locked SC-QAM Upstream 30300000 Hz 6400000 Hz 31.0 dBmV
2 1 Locked SC-QAM Upstream 17400000 Hz 6400000 Hz 29.0 dBmV
3 2 Locked SC-QAM Upstream 23900000 Hz 6400000 Hz 30.0 dBmV
4 4 Locked SC-QAM Upstream 36700000 Hz 6400000 Hz 31.0 dBmV


Current System Time: Thu Dec 26 16:16:51 2019

Date Time Event ID Event Level Description
12/26/2019 16:15 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
12/26/2019 06:32 68010300 4 "DHCP RENEW WARNING - Field invalid in response v4 option;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
12/26/2019 06:15 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
12/25/2019 11:09 74010100 6 "CM-STATUS message sent. Event Type Code: 24; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 3.;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
12/25/2019 11:08 74010100 6 "CM-STATUS message sent. Event Type Code: 16; Chan ID: 159; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 3.;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
12/25/2019 10:59 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
12/22/2019 08:39 84000500 3 "SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
12/22/2019 08:27 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
12/22/2019 08:27 67061600 6 "DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
12/22/2019 08:27 73040100 6 "TLV-11 - unrecognized OID;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
12/22/2019 08:27 68000300 5 "DHCP WARNING - Non-critical field invalid in response ;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00 2436694066 6 "Honoring MDD; IP provisioning mode = IPv4"
01/01/1970 00:00 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
12/22/2019 08:11 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
12/22/2019 06:53 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
12/21/2019 20:18 84000500 3 "SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
12/21/2019 20:06 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
12/21/2019 20:01 2436694044 3 "Resetting the cable modem due to docsDevResetNow"
12/21/2019 19:58 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
12/21/2019 19:55 2436694044 3 "Resetting the cable modem due to docsDevResetNow"
12/21/2019 19:40 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
12/21/2019 19:39 84000500 3 "SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
12/21/2019 19:35 82000500 3 "Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=70:6b:b9:00:a5:5a;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:01 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:01 84000200 3 "SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:01 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"
01/01/1970 00:00 2436694048 3 "Telnet user logged in from IP address 192.168.100.101."
01/01/1970 00:00 84000100 3 "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=14:c0:3e:01:76:a1;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;"

6 Replies

  • WorkingAtHome12's avatar
    WorkingAtHome12
    New Contributor II

    I think my issue has finally been resolved. Cox replaced the underground cables from the "tap" to the "bump" to my house.  Both the signal to noise ratio and the power levels decreased, but I haven't had any T3 timeouts or disconnects since them.  No warnings or error messages on the cable modem either.

  • WorkingAtHome12's avatar
    WorkingAtHome12
    New Contributor II

    Bumping this post since it was initially, incorrectly marked as spam.

    If any additional information is needed, please let me know.

  • Hello. Are there any splitters or signal amps on the cable line going to the modem? Also, has the modem been moved since the tech visit? -Allan, Cox Support Forums Moderator
    • WorkingAtHome12's avatar
      WorkingAtHome12
      New Contributor II

      Hello Allen. There isn't a single splitter in the house.  The modem has not moved.  There are no signal amps inside the house.

      • MariaL's avatar
        MariaL
        Moderator
        Hi WorkingAtHome123,

        We would like to further investigate this issue. Please email cox.help@cox.com for support. Be sure to include the following information:

        • Your full name
        • The account holder’s name if different from yours
        • Your complete address including city and state
        • Details regarding the nature of your issue including a link or reference to your forums post

        We look forward to receiving the requested information so that we may continue to assist you.

        Maria
        Cox Support Forum Moderator