Contributor
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45 Messages
Motorola MB8611 - Internet dropping/reboot - SYNC Timing Synchronization failure and No Ranging Response received - T3 time-out
Solved: I switched to Arris S33 and so far no issues with service or reboots. Still get occasional "RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW. Dynamic Range Window violation" messages in the logs but modem keeps working.
Update: Support has confirmed that this is Motorola software related issue - "In regard to the internet issue, there is a known issue with the specific modem you have, and until the firmware issue from Motorola is addressed, you may experience issues with the service."
I'm having the same SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing / No Ranging Response received - T3 time-out issue as many of the others reported on this forum.
This is very frustrating as my internet drops 3-4 times per day in the same time windows: between 11am and noon, around 3pm, around 6pm and sometimes around 11pm. It's almost like there is a pattern.
Motorola support tells me that this is a cable's provider issue and Xfinity support tells me (after modem is rebooted of course) there is nothing wrong with my line! This is beyond frustration as my work requires fast and stable internet and unfortunately Xfinity is the only provider in the area who has it (fast but not stable!).
My setup:
Cable length: ~130 feet. This consists of 30 feet of underground RG11 from the street box to the box on the side of the house and 100 feet of RG6 from the house box to cable modem (brand new, just replaced). No any connectors or splitters on the line, so this is not a cable issue on my property).
Modem: Motorola MB8611, software version 8611-21.3.7
WiFi router: ASUS AC1900 (RT-AC68U)
Here is the event log after the SYNC Timing Synchronization failure
Connection settings before the failure:
Connection settings after the failure:
user_fd33c8
Contributor
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45 Messages
1 year ago
Update: uptime is now 1 day 16 hours. One thing that I recall I did on Saturday is tightened both RG11 and RG6 cables on a coupler inside demarc box. I did have one reboot that night but after that things are stable so far.
My upstream power indeed fluctuates. Before noon it was 38 dB now it is 45 dB and yesterday it was 47 dB. That fluctuation corresponds with new event log messages "RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW". According to the author of this article https://www.duckware.com/tech/solving-intermittent-cable-modem-issues.html this may indicate a lose connector somewhere on the line. The only place left to inspect is the cable box on the sidewalk near my house from where RG11 originates. I will also be adding this ground block / surge protector https://www.amazon.com/gp/product/B0016AIYU6
(edited)
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NoGoodNamesLeft4Me
Contributor
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72 Messages
1 year ago
There should already be one outside your house with a wire leading to an earth ground (i.e., a long metal rod inserted into the ground). That's what the screw is for. If you don't have one, Xfinity should install one for free. My installation is new, and I have one.
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user_fd33c8
Contributor
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45 Messages
1 year ago
Update: My MB8611 has been up 5 days 8 hours. I checked the cable box on the sidewalk near my house and I was shocked - bunch of roots, dirt and dead roaches inside. I couldn't even see where is my cable. I guess will need Xfinity tech to come and clean that. I will be adding ground block/surge protector this afternoon since my line was not grounded nor protected by Xfinity.
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user_be3ca5
Contributor
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10 Messages
1 year ago
Hello All,
I'm still having the same exact issue with the MB8611 and Comcast. The T3 timeouts have been really bad the past couple of days, at least 10x each day. This issue has been happening on/off for almost 3 weeks. I've had a tech visit but that did not fix the issue. I've chatted with tech support but that did not fix the issue. It is awfully strange that so many people are experiencing this and there is no comment from official Comcast people telling us they are investigating. Everyone seems to get the run-around with this. This is a "Comcast approved" modem and it doesn't seem to be working so well. Perhaps this is the strongarm to get everyone to rent their Xfinity gateway.
I work from home and getting disconnected a couple of times per hour is unacceptable. I can't wait to get out of contract time so I can get a different provider who can provide reliable service. I have never had this many problems with internet in my life.
Over it.
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user_308158
Visitor
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1 Message
1 year ago
I have a MB8600 and for the past 2 months I have been having a ton of issues like many here. Everything used to be great but at this point the amount of drop outs is crazy. I can't even watch Youtube TV because all it does is buffer works for 1 min and then buffers another 20 seconds.
I do a speed test and I am seeing 200+mbs but having almost zero upload bandwidth. I have been on hold and with phone support 3 times and had one tech come to the house. They are sending another tech in a couple days. Any suggestions?
(Cross posted)
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user_fd33c8
Contributor
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45 Messages
1 year ago
After 5 days 12 hours of enjoying a stable internet my luck has ran out. Modem is dropping internet and rebooting multiple times per day. SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing errors again flooding my event log. I tend to believe this is not modem issue but a service / line issue.
If I can get a rental modem from Xfinity that would be great but to pay additional $14/month that's just not going to cut it.
I also ordered PPC FPA6-54 in-Line Forward Path Attenuator 6dB 75 Ohms. Will install this afternoon and see if that will do any good.
(edited)
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user_fd33c8
Contributor
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45 Messages
1 year ago
Interesting. Adding PPC FPA6-54 in-Line Forward Path Attenuator did decrease downstream power (now it's between 0.1 to -0.7) but upstream power almost did not change. It went up about 1dB (38-39dB as compared to 37-38dB before). Rebooted modem and cleared event log. Will see what's going to happen...
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user_fd33c8
Contributor
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45 Messages
1 year ago
Update: PPC FPA6-54 in-Line Forward Path Attenuator did not help. Two modem reboots last night and one this morning.
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user_fd33c8
Contributor
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45 Messages
1 year ago
Update: back to 3-4 reboots per day plus 2 reboots every night according to event log.
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emattheis
Visitor
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17 Messages
1 year ago
Just stumbled across this forum. Having a similar issue with my MB8611 (if not identical - haven't compared exact log messages...). My home is 5 years old on a brand new street. Comcast infrastructure at the street is about 7 years old. Line to my house is 5 years old. Everything is buried in conduit. Less than 6 feet of cable from the ground coupler outside to the cable modem inside. All connections wrench tight. Modem is new as of last March. Everything has been perfect until mid December when we started noticing the modem reconnecting unexpectedly. Lately it seems more frequent - at least at more inconvenient times. My wife and I both work from home and there's a good chance one of us is on a video conference at any given time during business hours, so it's very noticeable. Finally reported to Comcast yesterday and they got a tech out within a few hours, which was fantastic! He confirmed that everything in the house was fine (while simultaneously stressing that it could be my router, wifi, laptop, etc. - despite the fact that it's obviously the modem reconnecting). He did a line test and everything reports good. He checked everything on the outside of my house and the connection at the street and everything good there as well. Had several reconnects since he left. He said he would escalate to a line tech, but no idea when that will happen or if I will find out about it.
I don't want to replace a perfectly good modem, but I also can't keep losing internet in the middle of the work day and I really don't want to rent from Comcast. Does anyone know if there is commercially available DOCSIS 3.1 option that doesn't exhibit this problem on Comcast's network?
(edited)
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maloney40
New Poster
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3 Messages
1 year ago
I also have a Motorola Modem, MB8611 and have internet drops as well. I had a service technician out yesterday and said everything was good up until the modem.
Time
Priority
Description
Time Not Established
Critical (3)
CMSTATUS:US_Diplexer_Mode_Change:Fixed Initial, 5-42MHz.
Time Not Established
Critical (3)
SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.1;
Time Not Established
Critical (3)
CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.2, 258MHz.
Time Not Established
Critical (3)
CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.3, 1002MHz.
Time Not Established
Critical (3)
CMSTATUS:US_Diplexer_Mode_Change:TLV-21.1, 5-42MHz.
Time Not Established
Critical (3)
CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.2, 108MHz.
Time Not Established
Critical (3)
CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.3, 1002MHz.
Time Not Established
Critical (3)
CMSTATUS:US_Diplexer_Mode_Change:TLV-84.1, 5-42MHz.
12:49:22
Fri Jan 13 2023
Critical (3)
Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.1;
Time Not Established
Critical (3)
CMSTATUS:US_Diplexer_Mode_Change:Fixed Initial, 5-42MHz.
Time Not Established
Critical (3)
SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.1;
Time Not Established
Critical (3)
CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.2, 258MHz.
Time Not Established
Critical (3)
CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-21.3, 1002MHz.
Time Not Established
Critical (3)
CMSTATUS:US_Diplexer_Mode_Change:TLV-21.1, 5-42MHz.
Time Not Established
Notice (6)
Honoring MDD; IP provisioning mode = IPv6
Time Not Established
Critical (3)
CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.2, 108MHz.
Time Not Established
Critical (3)
CMSTATUS:DS_Diplexer_Mode_Change_Ignored:TLV-84.3, 1002MHz.
Time Not Established
Critical (3)
CMSTATUS:US_Diplexer_Mode_Change:TLV-84.1, 5-42MHz.
14:48:21
Fri Jan 13 2023
Notice (6)
DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.1;
14:48:27
Fri Jan 13 2023
Warning (5)
REG-RSP-MP Mismatch Between Calculated Value for P1.6hi Compared to CCAP Provided Value;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.1;
14:48:28
Fri Jan 13 2023
Warning (5)
RNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.1;
14:48:28
Fri Jan 13 2023
Warning (5)
Dynamic Range Window violation
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user_c5a405
Visitor
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10 Messages
1 year ago
I see your update. Since Xfinity/Motorola don't seem to be in a rush to fix the problem and I'm within 90 days of purchasing the modem; I'm returning my modem for a refund.
I have my old modem back online since about 2PM yesterday and thus far I've had no problems.
(edited)
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GUS_GuyUsingSystem
Visitor
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44 Messages
1 year ago
Mine has been acting up since 9.45 this AM for "No Ranging Response received - T3 time-out"
13x since original log was issued below.
But not actual 13x drop outs - but effectively 1 drop per 1. 5 hours now (mini buffering & internet outages) since this report was logged @ 9.45 AM.
(edited)
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user_fd33c8
Contributor
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45 Messages
1 year ago
Update: Started to get 5-6 drops and reboots per day. Super annoying. Can't wait till my contract is done.
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RobinData
Visitor
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3 Messages
1 year ago
Just to update - I returned my Motorola and got the latest Arris. After Xfinity reprovisioned it for me, everything works as it should now - and it is very, very fast. I've always liked Motorola, so this was disappointing. But, I can't complain about the speed and reliability now.
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