I recently came home from vacation on Sat, January 8th, and my internet kept dropping. I have a new Motorola MB8611 cable model that's been working since November 2021, connected to a Netgear wireless router. Computer connections are hard line ethernet. I've troubleshot for the last few days, and finally narrowed it down to my cable model constantly dropping connection, losing its Xfinity IP. The MB8611 cable modem error logs show reoccurring "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing" and "No Ranging Response received - T3 time-out" errors. The dropping seems to be much worse in the morning, and also seems to occur when I spike my bandwidth like trying to watch a video. The drops are random and unpredictable, and I can't seem to force it to happen.
I've called Xfinity support, but they tried to blame it on me, and said since my connection was up at the time of the call, there wasn't an issue. However, they did agree to have a technician come out on Jan 13th. I live in Colorado Springs, CO.
I'm seeing many, many other posts about this same type of issue happening over the last few weeks, and mostly with Motorola modems. Every Xfinity support response seems to be "cut and paste". Does Xfinity not see a potential pattern here and system wide problem?
Please help!
Event Log |
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Time |
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Priority |
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Description |
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Time Not Established |
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Critical (3) |
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SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1; |
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Time Not Established |
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Critical (3) |
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No Ranging Response received - T3 time-out;CM-QOS=1.1;CM-VER=3.1; |
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Time Not Established |
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Critical (3) |
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SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1; |
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09:53:42 Tue Jan 11 2022 |
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Critical (3) |
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SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1; |
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Time Not Established |
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Critical (3) |
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SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1; |
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Time Not Established |
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Critical (3) |
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No Ranging Response received - T3 time-out;CM-QOS=1.1;CM-VER=3.1; |
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Time Not Established |
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Critical (3) |
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SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1; |
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Time Not Established |
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Critical (3) |
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No Ranging Response received - T3 time-out;CM-QOS=1.1;CM-VER=3.1; |
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Time Not Established |
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Critical (3) |
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SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-QOS=1.1;CM-VER=3.1; |
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Time Not Established |
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Critical (3) |
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No Ranging Response received - T3 time-out;CM-QOS=1.1;CM-VER=3.1; |
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Time Not Established |
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Notice (6) |
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Honoring MDD; IP provisioning mode = IPv6 |
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10:16:03 Tue Jan 11 2022 |
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Notice (6) |
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DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-QOS=1.1;CM-VER=3.1; |
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10:16:25 Tue Jan 11 2022 |
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Notice (6) |
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CM-STATUS message sent. Event Type Code: 24; Chan ID: 48; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0.;CM-QOS=1.1;CM-VER=3.1; |
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EG
Expert
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106.3K Messages
3 years ago
What do the modem's signal stats look like ? Try getting them here; http://192.168.100.1
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.
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user_d6db27
Visitor
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9 Messages
3 years ago
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user_d6db27
Visitor
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9 Messages
3 years ago
I received a text message from Xfinity today stating, "We fixed the issue impacting Xfinity Internet in your area." At the time, it seemed to be stable, but again, the issue happens much more in the morning and not the afternoon. However, my issue remains.
Now, I've been able to force it to happen a few times if I run a speed test (speedtest.net). When it starts to test the upload speed, about 5 to 10 seconds into it, it kills the connection. My modem's xfinity IP drops, I lose all connectivity, modem's 192.168.100.1 IP becomes unreachable, after about a minute the modem issues me a 192.168.100.10 IP for about 2 minutes, and then finally re-picks up the Xfinity 75.50.*.* IP. Error logs in the modem show the same errors as mentioned above.
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EG
Expert
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106.3K Messages
3 years ago
The signal stats are ok / in spec but the error log entries indicate that something is going on. Perhaps there is noise ingress into the line(s) / an upstream channel-return path impairment 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 will be able to poll the CMTS to see whether or not everything is in the green zone, see your node / cable plant and modem health, and also see a history plot for the modem. You should get a reply here in your topic. Good luck !
(edited)
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user_d6db27
Visitor
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9 Messages
3 years ago
Ok, thank you. Standing by. Wondering if Xfinity is seeing this issue with other Motorola modems and the MB8611. Maybe its an Xfinity configuration issue for this modem, or a Motorola firmware issue?
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user_d6db27
Visitor
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9 Messages
3 years ago
Upload speed tests still breaking it. Doing it once it hits about 375mbps. My connection seems to be dropping less after this "fix" xfinity did with me doing my regular stuff in the morning. But speedtest seems to push the download/upload high enough to break it still.
(edited)
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user_766992
Visitor
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1 Message
3 years ago
Did this ever get resolved? I'm having the same issue. MB8611 as well. A technician came out and changed the ground block, took out one of the splitters, and changed the wall plate. still having the same problem. Very frustrating.
(edited)
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Brandon8791
Visitor
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6 Messages
3 years ago
I have been having this issue for awhile since december. I dont think that it is this modem specifically honestly. I have swapped out 3 different modems of my own, two xfinity modems and routers, and nothing has fixed it yet. Even swapped my nighthawk routers. I think personally something bigger is going on but good luck. I know I have quite a few departments involved... Engineering, Main line, maintenance, pretty positive actual corporate is involved and been replying to me as well. Their supposed to be constantly monitoring the modem, but idk if thats actually happening.
I will say that they are atleast attempting to fix the issue, but it sucks in the meantime. Even called Motorola and their Engineer who had been there 9 years said he hasn't seen an issue like mine. It is definitely weird.
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GSJ_2910ea
Visitor
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1 Message
3 years ago
I've been having the same issue with Motorola MB8611 on Comcast since I bought it in January. Motorola graciously replaced the modem in case some thing was unexpectedly wrong with the one I originally purchased. The issue remained. Comcast tech (level 2) came out last weekend and changed a splitter that he said should be different (originally installed by Comcast.) The issue has been worse this week. Level 5 tech came out today. He replaced the splitter the guy installed last week and replaced a ground wire. I've lost internet 3 times since he left 20 min ago. Lots of hours trying to get resolved and lots of frustration.
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eliezery
Visitor
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2 Messages
2 years ago
I am having the same issues as the users above...
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(edited)
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