Another Motorola MB8611 rebooting and losing WAN post

Please copy all of the text in its entirety of the *Downstream Power Levels*, the *SNR's* (Signal to Noise Ratios), and the *Upstream Power Level* numbers and paste them into your next post.

Please also post RF error log entries as well in their entirety (copy and paste them, don't post a screenshot) but redact the CM MAC and the CMTS MAC addresses for your privacy. They are considered to be personal information. Personally identifying information is a violation of their forum guidelines. The forum bot will not allow your post to be seen publically.

Hey there, @f2point8. Thank you for creating this post. I understand that the technicians state there are no issues with the lines, and I do not believe that signal issues would cause a restart of the device itself. Have you attempted using any other modems to verify if there are any issues with them? 

Edgardo, I am going to try another modem tomorrow if I can get ahold of one.  I did send the info from the modem to a support person at Motorola who says the problem is with the signal quality. I'm getting frustrated because this has quickly turned into a situation where Motorola and Xfinity are each pointing their fingers at each other as the problem.  

I think these are the numbers EG asked for... I hope I got all the MAC addresses cut out 

Downstream Bonded Channels

Channel Lock Status Modulation Channel ID Freq. (MHz) Pwr (dBmV) SNR (dB) Corrected Uncorrected    1 Locked QAM256 20 501.0 4.0 41.1 0 0    2 Locked QAM256 17 483.0 4.1 41.1 0 0    3 Locked QAM256 18 489.0 4.1 41.2 0 0    4 Locked QAM256 19 495.0 4.1 41.2 0 0    5 Locked QAM256 21 507.0 4.0 41.2 0 0    6 Locked QAM256 22 513.0 3.8 41.1 0 0    7 Locked QAM256 23 519.0 3.9 41.2 0 0    8 Locked QAM256 24 525.0 3.8 41.0 0 0    9 Locked QAM256 25 531.0 3.7 41.0 0 0    10 Locked QAM256 26 543.0 3.6 40.8 0 0    11 Locked QAM256 27 555.0 3.5 40.7 1 0    12 Locked QAM256 28 561.0 3.5 40.8 1 0    13 Locked QAM256 29 567.0 3.6 40.7 1 0    14 Locked QAM256 30 573.0 3.7 40.8 0 0    15 Locked QAM256 31 579.0 3.7 40.7 1 0    16 Locked QAM256 32 585.0 3.8 40.8 1 0    17 Locked QAM256 33 591.0 3.7 40.6 2 0    18 Locked QAM256 34 597.0 3.8 40.7 1 0    19 Locked QAM256 35 603.0 3.8 40.6 2 0    20 Locked QAM256 36 609.0 3.8 40.6 0 0    21 Locked QAM256 37 615.0 3.8 40.6 1 0    22 Locked QAM256 38 621.0 4.0 40.6 1 0    23 Locked QAM256 39 627.0 4.0 40.6 0 0    24 Locked QAM256 40 633.0 4.0 40.5 1 0    25 Locked QAM256 41 639.0 4.0 40.5 1 0    26 Locked QAM256 42 645.0 4.0 40.5 1 0    27 Locked QAM256 43 651.0 3.8 40.3 1 0    28 Locked QAM256 44 657.0 3.8 40.4 2 0    29 Locked QAM256 45 663.0 3.7 40.4 2 0    30 Locked QAM256 46 669.0 3.7 40.3 2 0    31 Locked QAM256 47 675.0 3.9 39.7 0 0    32 Locked OFDM PLC 48 722.0 4.4 40.3 359921532 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 16.4 48.3    2 Locked SC-QAM 2 5120 22.8 49.0    3 Locked SC-QAM 3 5120 29.2 49.3    4 Locked SC-QAM 4 5120 35.6 49.8

Event Log

Time    Priority    Description      Time Not Established   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-CM-QOS=1.1;CM-VER=3.1;     00:31:56 Fri Dec 24 2021   Critical (3)   SYNC Timing Synchronization failure - Loss of Sync;;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=;CMTS-CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-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-M-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-M-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-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-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;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-;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-CMTS-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-;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-;CMTS-;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-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-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-CMTS-;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-;CMTS-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-;CMTS-;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   No Ranging Response received - T3 time-out;CM-;CMTS-CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Critical (3)   SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;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-;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-;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-;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-;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-;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-;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-;CM-QOS=1.1;CM-VER=3.1;     Time Not Established   Notice (6)   Honoring MDD; IP provisioning mode = IPv6     20:17:31 Sat Dec 25 2021   Notice (6)   DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-S-CM-QOS=1.1;CM-VER=3.1;     20:17:51 Sat Dec 25 2021   Notice (6)   CM-STATUS message sent. Event Type Code: 24; Chan ID: 48; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0.;CM-;CM-QOS=1.1;CM-VER=3.1;

The upstream power is on the high side and it may be intermittently fluctuating even higher to out of spec levels. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In an 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 5-1000 MHz, bi-directional, and no gold colored garbage from Radio Shack, Home Depot, Target, etc. Splitters should be swapped with known to be good / new ones to test.

Also check the coax cable for any damage such as cuts, nicks, kinks, sharp bends, etc.

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.

Good luck with it !

Thank you for the info. I don’t have any splitters on the incoming cable. Since I have had techs from Xfinity out twice who said the line was good, I wanted to try something else. I got a less expensive Netgear CM700 modem that’s DOCSIS 3.0 instead of 3.1 of the Motorola, it has now been up for 26 hours straight with no hiccups or reboots whatsoever (compared with every hour or two of the Motorola MB8611 rebooting). I can’t figure out why this would be. Does the Netgear working better prove that it’s not the line? Or is the problem in the line going to cause the Netgear to fail over time as well? I’d rather keep the Motorola since it’s more future proof with a higher standard and 2.5 Gbps network capability (which I don’t have yet in my home devices but maybe in the future) for only $25 more than the Netgear, but reliability is the most important. 

Some modems are more forgiving of less than stellar connection quality conditions than are others.

Thank you, EG. Do you know of any settings on the MB8611 I could do that might lower its intolerance a bit (even it it lowers its performance slightly?) Or now that it seems much more stable with the Netgear modem should I just stick with that? I'm wondering about still having the Xfinity people out one more time to have them check out my line. 

This is the upstream data as reported on my Netgear device (since you mentioned it was too high on the Motorola). Can upstream power vary by modem and not just the line? 

@customerbob 

Please create a new topic of your own here on this board detailing your issue (copy and paste your post there). Thanks. The original poster has not returned. 5-month-old dead thread is now being closed.