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SYNC Timing Synchronization failure AND No Ranging Response // HELP???

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SYNC Timing Synchronization failure AND No Ranging Response // HELP???

A couple of weeks ago started to have intermittent connection issues. (PALO ALTO, CA)  First Comcast suspected a hardware issue and sent me a new device that didn't help. (I tried a total of 3 different routers)  

 

So I went and bought my own Netgear C7800 and now I have access to more detailed logs: 

 

 

Time Not Established Notice (6) Honoring MDD; IP provisioning mode = IPv6
Time Not Established Critical (3) No Ranging Response received - T3 time-out;CM-MAC=[HIDDEN];CMTS-MAC=[HIDDEN];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=cc:[HIDDEN];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=cc:[HIDDEN];CMTS-MAC=[HIDDEN];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=cc:[HIDDEN];CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;

 

<tabindex=-1>Startup Procedure</tabindex=-1>
Procedure Status Comment
Acquire Downstream Channel 525000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Security ENABLED BPI+
IP Provisioning Mode Honor MDD IPv6 only

<tabindex=-1>Downstream Bonded Channels</tabindex=-1>
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectabables
1 Locked QAM256 20 525000000 Hz 2.3 dBmV 41.3 dB 0 0
2 Locked QAM256 8 447000000 Hz 2.9 dBmV 41.7 dB 0 0
3 Locked QAM256 9 453000000 Hz 2.9 dBmV 41.6 dB 0 0
4 Locked QAM256 10 459000000 Hz 2.9 dBmV 41.6 dB 0 0
5 Locked QAM256 11 465000000 Hz 2.8 dBmV 41.6 dB 0 0
6 Locked QAM256 12 471000000 Hz 2.8 dBmV 41.5 dB 0 0
7 Locked QAM256 13 477000000 Hz 2.8 dBmV 41.5 dB 0 0
8 Locked QAM256 14 483000000 Hz 2.7 dBmV 41.6 dB 0 0
9 Locked QAM256 15 489000000 Hz 2.8 dBmV 41.4 dB 0 0
10 Locked QAM256 16 495000000 Hz 2.5 dBmV 41.1 dB 0 0
11 Locked QAM256 17 507000000 Hz 2.4 dBmV 41.1 dB 0 0
12 Locked QAM256 18 513000000 Hz 2.5 dBmV 41.2 dB 0 0
13 Locked QAM256 19 519000000 Hz 2.5 dBmV 41.1 dB 0 0
14 Locked QAM256 21 531000000 Hz 2.4 dBmV 41.0 dB 0 0
15 Locked QAM256 22 537000000 Hz 2.2 dBmV 41.1 dB 0 0
16 Locked QAM256 23 543000000 Hz 2.1 dBmV 41.0 dB 0 0
17 Locked QAM256 24 549000000 Hz 2.3 dBmV 41.2 dB 0 0
18 Locked QAM256 25 555000000 Hz 2.1 dBmV 40.9 dB 0 0
19 Locked QAM256 26 561000000 Hz 2.1 dBmV 40.9 dB 0 0
20 Locked QAM256 27 567000000 Hz 2.0 dBmV 41.0 dB 0 0
21 Locked QAM256 28 573000000 Hz 1.9 dBmV 41.0 dB 0 0
22 Locked QAM256 29 579000000 Hz 1.9 dBmV 40.9 dB 0 0
23 Locked QAM256 30 585000000 Hz 1.7 dBmV 40.9 dB 0 0
24 Locked QAM256 31 591000000 Hz 1.7 dBmV 40.9 dB 0 0
25 Locked QAM256 32 597000000 Hz 1.7 dBmV 40.9 dB 0 0
26 Locked QAM256 33 603000000 Hz 1.7 dBmV 40.8 dB 0 0
27 Locked QAM256 34 609000000 Hz 1.5 dBmV 41.0 dB 0 0
28 Locked QAM256 35 615000000 Hz 1.3 dBmV 40.8 dB 0 0
29 Locked QAM256 36 621000000 Hz 1.2 dBmV 40.6 dB 0 0
30 Locked QAM256 37 627000000 Hz 0.7 dBmV 40.5 dB 0 0
31 Locked QAM256 38 633000000 Hz 0.7 dBmV 40.5 dB 0 0
32 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0

<tabindex=-1>Upstream Bonded Channels</tabindex=-1>
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked ATDMA 10 1280 Ksym/sec 41200000 Hz 42.0 dBmV
2 Locked ATDMA 7 5120 Ksym/sec 23700000 Hz 40.3 dBmV
3 Locked ATDMA 9 5120 Ksym/sec 36700000 Hz 40.5 dBmV
4 Locked ATDMA 8 5120 Ksym/sec 30300000 Hz 40.5 dBmV
5 Locked ATDMA 6 5120 Ksym/sec 17300000 Hz 39.8 dBmV
6 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0 dBmV
7 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0 dBmV
8 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0 dBmV

 

In addition, I noticed that after the errors above I noticed that it's not actually the internet or connection dropping it appears that the router is unable to assign an IPv4 address or the devices don't seem to "accept them" - I have no idea why= maybe it has to do with the time sync issue. 

 

- All devices are set to get their IP address automatically via DHCP.

- It affects both ethernet and wifi connected devices 

- There are no IP conflict devices simply don't "accept/lose"  their Ipv4 address

- IPv6 address seems to be assigned fine but this might be due to the standard setting of my router for Ipv6 

IPv6 Address Assignment
Auto Config
Use DHCP Server

- Renewing DCHP lease doesn't seem to have any effect 

- Restarting the modem doesn't seem to really help

- The modem/router is set to be DHCP server 

- there is no WIFI interference

- I also had a technician here already who confirmed that the connection to the house and to the modem is stable without any loss 

- I also ruled out hardware issues as I tried the connection with 3 different devices  (all of which I of course added and removed via Xfinity Customer support) 2 were Xfinity rented devices and the current one is a Netgear C7800 

- Firmware is up-to-date 

 

About 48h ago the issues seemed to have "fixed itself" for about 24h but returned yesterday afternoon. For the last 2 weeks, I wasn't able to reliably use my internet for about 90% of the time 

 

I spent a total of 9h-13h with various support lines without any luck- I have another technician appointment today. but honestly not much hope for that to solve the issue. 

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Re: SYNC Timing Synchronization failure AND No Ranging Response // HELP???

UPDATE: 

 

The technician came out today and we checked every single wire, even went into the crawl space and we went as far and connected the modem outside to make sure there is no issue with any of the cables. 

 

We lastly went and reactivated the rental modem I still have in the house to rule out any hardware issue. After 1.5h the issue was still not fixed and the technician left without any further ideas and suggested calling support again. 

 

I'm out of ideas and what seems like out of options and still stuck without the internet.