CAX30 Timing Synchronization failure - Loss of Sync

Question

I have a Nighhawk AX6 CAX30 AC2700 router that is dropping connection.

I have read through all the canned responses for this issue.

I have Firmware Version V1.4.10.8

There is no splitter

There is no amplifier

The coax is brand new from the node

I am on Comcast/XFinity. Xfinity has been out 3 or 4 times because i keep complaining. They have done all they can do with the line. They gave me an xfi modem and set up a monitor. The week that it was active there was not a single event of dropping the connection.

On 12/15 I spent time on a call with Netgear support on which we performed the following:

Disconnect all but power connection

Press and hold reset button for 30 seconds

Remove poer connection

Press and hold reset button for 30 seconds

Reconnect power

Press and hold reset button for 30 seconds.

The modem worked fine for 3 days and now is back to dropping connection

A review of the logs shows this:

2021-12-19 13:05:52	Notice (6)	DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=6c:cd:d6:80:fb:a4;CMTS-MAC=00:01:5c:92:1a:66;CM-QOS=1.1;CM-VER=3.1;
1970-01-01 00:00:35	Notice (6)	Honoring MDD; IP provisioning mode = IPv6
1970-01-01 00:00:30	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=6c:cd:d6:80:fb:a4;CMTS-MAC=00:01:5c:92:1a:66;CM-QOS=1.1;CM-VER=3.1;
1970-01-01 00:00:24	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;CM-MAC=6c:cd:d6:80:fb:a4;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
2021-12-19 12:20:14	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=6c:cd:d6:80:fb:a4;CMTS-MAC=00:01:5c:92:1a:66;CM-QOS=1.1;CM-VER=3.1;
2021-12-19 12:20:06	Critical (3)	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=6c:cd:d6:80:fb:a4;CMTS-MAC=00:01:5c:92:1a:66;CM-QOS=1.1;CM-VER=3.1;

The cable connection info is this:

Cable Connection

Cancel Apply

Frequency start Value

This field below allows you to modify the frequency the cable modem start with its scan during initialization and registration. Enter the new start frequency and restart the cable modem for it to take effect.

Starting Frequency

<tabindex=-1>Startup Procedure</tabindex=-1>

Procedure	Status	Comment
Acquire Downstream Channel	507000000 Hz	Locked
Connectivity State	OK	Registration Complete
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	256 QAM	5	507000000 Hz	4.9 dBmV	42.6 dB	0	0
2	Locked	256 QAM	2	483000000 Hz	4.7 dBmV	42.5 dB	0	0
3	Locked	256 QAM	3	489000000 Hz	4.8 dBmV	42.7 dB	0	0
4	Locked	256 QAM	4	495000000 Hz	4.6 dBmV	42.4 dB	0	0
5	Locked	256 QAM	6	513000000 Hz	4.5 dBmV	42.4 dB	0	0
6	Locked	256 QAM	7	519000000 Hz	4.4 dBmV	42.2 dB	0	0
7	Locked	256 QAM	8	525000000 Hz	4.7 dBmV	42.4 dB	0	0
8	Locked	256 QAM	9	531000000 Hz	4.9 dBmV	42.5 dB	0	0
9	Locked	256 QAM	10	537000000 Hz	5.0 dBmV	42.5 dB	0	0
10	Locked	256 QAM	11	543000000 Hz	4.8 dBmV	42.4 dB	0	0
11	Locked	256 QAM	12	549000000 Hz	4.5 dBmV	42.3 dB	0	0
12	Locked	256 QAM	13	555000000 Hz	4.5 dBmV	42.3 dB	0	0
13	Locked	256 QAM	14	561000000 Hz	4.6 dBmV	42.4 dB	0	0
14	Locked	256 QAM	15	567000000 Hz	4.8 dBmV	42.4 dB	0	0
15	Locked	256 QAM	16	573000000 Hz	4.8 dBmV	42.3 dB	0	0
16	Locked	256 QAM	17	579000000 Hz	4.8 dBmV	42.3 dB	0	0
17	Locked	256 QAM	18	585000000 Hz	4.8 dBmV	42.4 dB	0	0
18	Locked	256 QAM	19	591000000 Hz	4.9 dBmV	42.4 dB	0	0
19	Locked	256 QAM	20	597000000 Hz	5.3 dBmV	42.5 dB	0	0
20	Locked	256 QAM	21	603000000 Hz	5.3 dBmV	42.4 dB	0	0
21	Locked	256 QAM	22	609000000 Hz	5.2 dBmV	42.4 dB	0	0
22	Locked	256 QAM	23	615000000 Hz	5.2 dBmV	42.4 dB	0	0
23	Locked	256 QAM	24	621000000 Hz	5.3 dBmV	42.3 dB	0	0
24	Locked	256 QAM	25	627000000 Hz	5.4 dBmV	42.4 dB	0	0
25	Locked	256 QAM	26	633000000 Hz	5.6 dBmV	42.3 dB	0	0
26	Locked	256 QAM	27	639000000 Hz	5.3 dBmV	42.4 dB	0	0
27	Locked	256 QAM	28	645000000 Hz	5.4 dBmV	42.5 dB	0	0
28	Locked	256 QAM	29	651000000 Hz	5.4 dBmV	42.1 dB	0	0
29	Locked	256 QAM	30	657000000 Hz	5.3 dBmV	42.2 dB	0	0
30	Locked	256 QAM	31	663000000 Hz	5.5 dBmV	42.2 dB	0	0
31	Locked	256 QAM	32	669000000 Hz	5.4 dBmV	42.2 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	1	1280 Ksym/sec	35600000 Hz	42.3 dBmV
2	Locked	ATDMA	2	1280 Ksym/sec	29200000 Hz	42.3 dBmV
3	Locked	ATDMA	3	1280 Ksym/sec	22800000 Hz	41.0 dBmV
4	Locked	ATDMA	4	1280 Ksym/sec	16400000 Hz	40.3 dBmV
5	Locked	ATDMA	5	1280 Ksym/sec	39600000 Hz	43.0 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

<tabindex=-1>Downstream OFDM Channels</tabindex=-1>

Channel	Channel ID	Indicator	Subcarrier Zero Frequency	Active Subcarrier Number Range	Total Codewords	Uncorrectable Codewords
1	37	Non-Primary	617.6 MHz	1108 ~ 2987	11416467	0
2	0	Other	0 MHz	0 ~ 0	0	0

<tabindex=-1>Upstream OFDMA Channels</tabindex=-1>

Channel	UpstreamIsMuted	Ranging Status	Subcarrier Zero Frequency	Active Subcarrier Number Range	Symbols Per Frame	Tx Power
1		Other	0 MHz	0 ~ 0	0	0 dBmV
2		Other	0 MHz	0 ~ 0	0	0 dBmV

Current System Time: 2021-12-19 14:00:36

System Up Time: 00:56:20

It is rather frustrating that such a high-end router is actually not as good as I was lead to believe by the reviews and ratings.

ljmagyar · Answer

please stop hijacking my thread with a problem that is not the same issue

FURRYe38 · Answer

Try a different CAX modem? If all as been checked and tried, possible faulty unit is all.&nbsp;

ljmagyar · Answer

Still dropping with sync errors.&nbsp; Is this normal at all? Is there any reason that I should need to reboot the modem periodically?&nbsp; With my ATT modem (previous house) i never had to reboot.&nbsp; The XFinity modem does not crash either.&nbsp; I don't want to use it or pay the extra $$ to do so, and it has less wifi range than the Netgear CAX30

ljmagyar · Answer

So after a lengthy chat with netgear support, they have told me that my downstream power is too weak. They told me that it is supposed to be between -7 dBmV and +7 dBmV. Mine is running between 4 and 5 dBmV (see above info).

If I am at +4 or +5 dBmV, how is that too weak when the recommended band is MINUS 7 to PLUS 7 dBmV? It must have been a language thing because "Sharon" and "Fatima" told me it is too weak at PLUS 4.

They quoted me this FAQ: https://kb.netgear.com/24311/Power-level-guidelines-for-a-NETGEAR-cable-modem-router

"Good Downstream power levels are within -7 to +7 dBmV."

FURRYe38 · Answer

Yes.
Have the ISP check the signal and line quality UP to the modem.&nbsp;Be sure the ISP provisions the modem correctly.Be sure there are no coax cable line splitters in the between the modem and ISP service box.&nbsp;Be sure your using good quality RG6 coax cable up to the modem.
&nbsp;
Your modem should not need a reboot or power cycle to correct anything unless your troubleshooting something.&nbsp;

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CAX30 Timing Synchronization failure - Loss of Sync

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