Have to reboot modem, at least daily to get my 1GIG tier. (Goes to 50mpbs download)

[robby69]

(Have Comcast gigabit service), Max speed I get hardwired ever was 800+.  Usually hovers around 600.  Have to reboot every day or two, otherwise download speed drops to 50mbps, upload speed remains constant at 42mbps.  Rebooting modem "fixes" issue.  The speed dropping and having to do a reboot to fix it is my issue.  Got a new modem in december compatible with new gigabit service.  Old modem with 300mbs service was rock solid.

https://www.speedtest.net/my-result/d/2109f6d2-c839-481e-8ff3-915eea3ec0c8

Connection

Startup Sequence        Startup Step Status Comment       Acquire Downstream Channel 549000000 Hz Locked       Upstream Connection OK Operational       Boot State OK Operational       Configuration File OK         Security Enabled BPI+       Connection Status        System Up Time 0 days 00h:20m:07s         Network Access Allowed         Downstream Bonded Channels         Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected    1 Locked QAM256 13 549.0 3.5 42.2 0 0    2 Locked QAM256 10 531.0 2.0 40.0 0 0    3 Locked QAM256 11 537.0 3.3 42.1 0 0    4 Locked QAM256 12 543.0 3.3 42.0 0 0    5 Locked QAM256 14 555.0 3.5 42.1 0 0    6 Locked QAM256 15 561.0 3.6 42.2 0 0    7 Locked QAM256 16 567.0 3.4 42.2 0 0    8 Locked QAM256 17 573.0 3.0 42.0 0 0    9 Locked QAM256 18 579.0 2.8 42.0 0 0    10 Locked QAM256 19 585.0 3.3 42.0 0 0    11 Locked QAM256 20 591.0 3.7 42.3 0 0    12 Locked QAM256 21 597.0 3.9 42.2 0 0    13 Locked QAM256 22 603.0 4.0 42.2 0 0    14 Locked QAM256 23 609.0 3.8 42.1 0 0    15 Locked QAM256 24 615.0 3.6 41.8 0 0    16 Locked QAM256 25 621.0 3.9 41.9 0 0    17 Locked QAM256 26 627.0 3.9 41.8 0 0    18 Locked QAM256 27 633.0 4.1 41.7 0 0    19 Locked QAM256 28 639.0 4.2 41.7 0 0    20 Locked QAM256 29 645.0 4.2 41.9 0 0    21 Locked QAM256 30 651.0 4.2 41.7 0 0    22 Locked QAM256 31 657.0 4.1 41.7 0 0    23 Locked QAM256 32 663.0 3.8 41.7 0 0    24 Locked QAM256 33 669.0 3.7 41.5 0 0    25 Locked QAM256 34 675.0 3.3 41.4 0 0    26 Locked QAM256 35 681.0 3.1 41.3 0 0    27 Locked QAM256 36 687.0 2.9 41.2 0 0    28 Locked QAM256 37 693.0 2.6 41.0 0 0    29 Locked QAM256 38 699.0 2.0 40.6 0 0    30 Locked QAM256 39 705.0 1.8 40.6 0 0    31 Locked QAM256 40 711.0 2.1 40.6 0 0    32 Locked OFDM PLC 41 762.0 0.9 39.6 5978565 0    Upstream Bonded Channels         Channel Lock Status Channel Type Channel ID Symb. Rate (Ksym/sec) Freq. (MHz) Pwr (dBmV)    1 Locked SC-QAM 1 5120 35.6 45.3    2 Locked SC-QAM 2 5120 29.2 45.3    3 Locked SC-QAM 3 5120 22.8 44.3    4 Locked SC-QAM 4 5120 16.4 44.3    5 Locked SC-QAM 5 2560 40.4 43.3    Downstream Frequency Setting        Downstream Frequency Select

LAG Enable/Disable

LAG(Link Aggregation Group, or Ethernet Port Bonding)  Disable Enable

[EG]

The signal stats looked o/k at that snapshot in time. Are there any error log entries being shown ? If so, please post them in their entirety.

What is the exact make and model number of the modem ?

[robby69]

After I rebooted early this morning when it was 80mbps, it went to 700-800

Few hours later now:

Xfinity.speedtest. com showing 380mbps on 1Gig connection

Speedtest.net peaks at 600mbps then drops to 360mpbs at end of test

uploads on both are steady at 42mbps

Modem is Motorola MB8600 docsis 3.1 (installed earlier this year) and speeds were consistently around 800+mbps, occassionally going to 900.

Here is event log

Event Log

Event Log

Time    Priority    Description      Time Not Established   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     14:07:51 Wed Jan 6 2021   Critical (3)   SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     03:51:40 Thu Jan 7 2021   Critical (3)   SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     03:51:46 Thu Jan 7 2021   Critical (3)   No Ranging Response received - T3 time-out;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     14:51:21 Fri Jan 8 2021   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     19:10:13 Wed Jan 13 2021   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     04:27:31 Mon Jan 18 2021   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     05:27:25 Tue Feb 2 2021   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     23:45:47 Sat Feb 6 2021   Critical (3)   Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     16:47:01 Sun Feb 7 2021   Critical (3)   Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     20:04:22 Mon Feb 8 2021   Critical (3)   Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Notice (6)   Honoring MDD; IP provisioning mode = IPv6     07:49:41 Fri Feb 12 2021   Notice (6)   DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=00:40:36:6f:8a:67;CMTS-MAC=00:01:5c:74:04:6e;CM-QOS=1.1;CM-VER=3.1;

[EG]

Even though the signal stats looked o/k at that snapshot in time, the error log entries confirm that something is going on. Perhaps there is noise ingress into the line(s) somewhere.

There are other signal stat figures that can't be read by the modem. 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.

I'm going to escalate your issue to the Comcast corporate employees that are available to these boards. They can check the CMTS (Cable Modem Termination System) for any real time degradation and / or error reports, see your node / cable plant and modem health, and see whether or not everything is in the green zone. They can also see a history plot for the modem and poll for those upstream receive signal stats.

You should get a reply here in your topic. Good luck !

[robby69]

Thanks for your help.  I had 300mbps with surfboard modem and had no issues.  Only reason I wen to Gigabit was because it was $10 cheaper since I went off 1yr 300mpbs contract.  I have not had any issues with Comcast except for the occassional outage. 

[EG]

Quite welcome !