Internet going in/out due to "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing"

Hello, seeking help with an internet issue. I work for a call center remotely, and throughout the day I have dropped calls. At the time of the dropped call I will get modem errors such as these, and when doing a ping test I get packet loss for very short period of time. I have read else where this might be a signal strength issue. My modem/router is Motorola - MG8702. Any help on this would be greatly appreciated, and let me know if you need more info.

Event Log

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-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;
02:34:13 Tue Oct 31 2023	Critical (3)	SYNC Timing Synchronization failure - Loss of Sync;
Time Not Established	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;
09:09:03 Thu Nov 16 2023	Critical (3)	SYNC Timing Synchronization failure - Loss of Sync;;CM-QOS=1.1;CM-VER=3.1;
09:09:08 Thu Nov 16 2023	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-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-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-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	Notice (6)	Honoring MDD; IP provisioning mode = IPv6
20:47:07 Fri Dec 8 2023	Notice (6)	DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;;CM-QOS=1.1;CM-VER=3.1;
23:45:52 Sun Dec 17 2023	Notice (6)	CM-STATUS message sent. Event Type Code: 23; Chan ID: 48; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;;CM-QOS=1.1;CM-VER=3.1;
23:45:52 Sun Dec 17 2023	Notice (6)	CM-STATUS message sent. Event Type Code: 20; Chan ID: 48; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;;CM-QOS=1.1;CM-VER=3.1;
23:45:54 Sun Dec 17 2023	Notice (6)	CM-STATUS message sent. Event Type Code: 16; Chan ID: 48; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 0 1 2 3.;;CM-QOS=1.1;CM-VER=3.1;
23:46:17 Sun Dec 17 2023	Notice (6)	CM-STATUS message sent. Event Type Code: 22; Chan ID: 48; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;;CM-QOS=1.1;CM-VER=3.1;
23:46:25 Sun Dec 17 2023	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-QOS=1.1;CM-VER=3.1;

Downstream Bonded Channels

Channel	Lock Status	Modulation	Channel ID	Freq. (MHz)	Pwr (dBmV)	SNR (dB)	Corrected	Uncorrected
1	Locked	QAM256	20	555.0	8.7	40.9	0	0
2	Locked	QAM256	17	537.0	7.9	40.7	0	0
3	Locked	QAM256	18	543.0	9.0	40.8	0	0
4	Locked	QAM256	19	549.0	7.8	40.6	0	0
5	Locked	QAM256	21	561.0	7.4	40.5	0	0
6	Locked	QAM256	22	567.0	8.4	40.7	0	0
7	Locked	QAM256	23	573.0	8.1	40.5	0	0
8	Locked	QAM256	24	579.0	8.6	40.6	0	0
9	Locked	QAM256	25	585.0	8.5	40.7	0	0
10	Locked	QAM256	26	591.0	8.4	40.7	0	0
11	Locked	QAM256	27	597.0	8.6	40.6	0	0
12	Locked	QAM256	28	603.0	7.8	40.5	0	0
13	Locked	QAM256	29	609.0	7.7	40.5	0	0
14	Locked	QAM256	30	615.0	7.4	40.3	0	0
15	Locked	QAM256	31	621.0	7.7	40.4	0	0
16	Locked	QAM256	32	627.0	6.9	40.2	0	0
17	Locked	QAM256	33	633.0	7.4	40.4	0	0
18	Locked	QAM256	34	639.0	7.0	40.2	0	0
19	Locked	QAM256	35	645.0	8.9	40.9	0	0
20	Locked	QAM256	36	651.0	8.0	40.4	0	0
21	Locked	QAM256	37	657.0	8.9	40.5	0	0
22	Locked	QAM256	38	663.0	8.5	40.5	0	0
23	Locked	QAM256	39	669.0	8.8	40.2	0	0
24	Locked	QAM256	40	675.0	9.0	39.3	109	2
25	Locked	QAM256	41	681.0	8.4	40.1	257	19
26	Locked	QAM256	42	687.0	9.1	40.0	187	37
27	Locked	QAM256	43	693.0	8.0	39.8	0	0
28	Locked	QAM256	44	699.0	8.8	39.9	0	0
29	Locked	QAM256	45	705.0	7.7	39.6	0	0
30	Locked	QAM256	46	711.0	8.6	39.8	0	0
31	Locked	QAM256	47	717.0	8.9	40.0	0	0
32	Locked	OFDM PLC	48	805.0	10.3	39.6	-441603775	68

Responses

EG

Expert

•

110.1K Messages

1 year ago

This may or may not be the root cause of the problem (YMMV) but the downstream power is a bit on the high / strong side.

Please also copy all of the text in its entirety of the *Upstream Power Level* numbers and paste them into your next post.

1

0

EG

Expert

•

110.1K Messages

1 year ago

Those are in spec. As stated, the higher downstream power may not be the root cause of the problem but here is some stuff that you can try and see;

Is there a drop amplifier on the coax cable line leading to the modem ? If so, try removing / bypassing it and see. If not, you can try installing a -6 dB forward path-only attenuator pad such as this one on the coax port on the rear of the modem to knock that power level down and see;

https://www.amazon.com/FPA6-54-Forward-Attenuator-DOCSIS-Internet/dp/B08KTRC3XZ

It won't affect the upstream power level which is within spec.

Please post back with how it goes. If you still have the problem I will escalate this to the Comcast Corporate Employees here.

(edited)

1

0

U

user_jn7ahv

4 Messages

Would this one work? https://www.amazon.com/6db-Attenuator-Pad-1-each/dp/B0013L48XA/ref=sr_1_3?keywords=-6+dB+forward+path-only+attenuator+pad&sr=8-3

1 year ago

0

EG

Expert

•

110.1K Messages

1 year ago

No. That's an overall attenuator pad. It going to raise the upstream power close to being out of spec which is something that we don't want to do. Try the one that I linked to.

2

0

U

user_jn7ahv

4 Messages

Gotcha, the one you linked to isn't available any more. Do you have any other recommendations? Specifically one that would arrive quicker?

1 year ago

0

XfinityBenny

Official Employee

•

790 Messages

@user_jn7ahv Looks like there is one available with the exact same name and specs in the top left corner in the Amazon link that EG posted. The page says it can arrive within 6 days with shipping. If that doesn't work or you don't find one, let us know. We can troubleshoot and get a tech out asap if it isn't resolved remotely!

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1 year ago

0

Your Home Network

user_jn7ahv

Internet going in/out due to "SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing"

EG

EG

user_jn7ahv

EG

user_jn7ahv

XfinityBenny

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