C7000 v2 inconsistent download speeds - 2.0-300.0 Mbps

Relyt · ‎2022-05-06

Hello,

I have been experiencing bad download speeds for several weeks and it is getting worse. I have spoken to several Comcast phone and chat associates trying to fix the issue with no luck.

I have tried power cycling my modem/router several times, factory resetting the modem/router and forgetting the WIFI networks and reconnecting with devices. The modem/router is directly connected to the wall with no splitter.

Thanks for your time.

Modem/Router - Netgear Nighthawk C7000 v2 - purchased/installed Nov 2021

Below are logs.

Downstream Bonded Channels

Channel	Lock Status	Modulation	Channel ID	Frequency	Power	SNR	Correctables	Uncorrectables
1	Locked	QAM256	24	549000000 Hz	-1.7 dBmV	38.5 dB	0	0
2	Locked	QAM256	25	555000000 Hz	-1.4 dBmV	38.8 dB	0	0
3	Locked	QAM256	26	561000000 Hz	-1.4 dBmV	38 dB	0	0
4	Locked	QAM256	27	567000000 Hz	-1.5 dBmV	38.7 dB	0	0
5	Locked	QAM256	28	573000000 Hz	-1.6 dBmV	38.6 dB	0	0
6	Locked	QAM256	29	579000000 Hz	-1.9 dBmV	38.2 dB	0	0
7	Locked	QAM256	30	585000000 Hz	-2 dBmV	38.4 dB	0	0
8	Locked	QAM256	31	591000000 Hz	-1.9 dBmV	37.8 dB	0	0
9	Locked	QAM256	32	597000000 Hz	-1.7 dBmV	38.2 dB	0	0
10	Locked	QAM256	33	603000000 Hz	-2 dBmV	38.2 dB	0	0
11	Locked	QAM256	34	609000000 Hz	-2.3 dBmV	37.7 dB	0	0
12	Locked	QAM256	35	615000000 Hz	-2.4 dBmV	38.2 dB	0	0
13	Locked	QAM256	36	621000000 Hz	-2.7 dBmV	37.8 dB	0	0
14	Locked	QAM256	37	627000000 Hz	-2.6 dBmV	38.1 dB	0	0
15	Locked	QAM256	38	633000000 Hz	-2.6 dBmV	38.3 dB	0	0
16	Locked	QAM256	39	639000000 Hz	-2.9 dBmV	37.5 dB	0	0
17	Locked	QAM256	40	645000000 Hz	-3.4 dBmV	37.8 dB	0	0
18	Locked	QAM256	41	651000000 Hz	-4 dBmV	37.4 dB	0	0
19	Locked	QAM256	42	657000000 Hz	-4 dBmV	37.4 dB	0	0
20	Locked	QAM256	43	663000000 Hz	-4.1 dBmV	37.5 dB	0	0
21	Locked	QAM256	44	669000000 Hz	-4.1 dBmV	36.8 dB	0	0
22	Locked	QAM256	45	675000000 Hz	-4 dBmV	37.1 dB	0	0
23	Locked	QAM256	46	681000000 Hz	-4.3 dBmV	36.7 dB	0	0
24	Locked	QAM256	47	687000000 Hz	-4.1 dBmV	37.1 dB	0	0

Upstream Bonded Channels

Channel	Lock Status	US Channel Type	Channel ID	Symbol Rate	Frequency	Power
1	Locked	ATDMA	5	5120 Ksym/sec	35600000 Hz	45.3 dBmV
2	Locked	ATDMA	2	5120 Ksym/sec	16400000 Hz	44.8 dBmV
3	Locked	ATDMA	3	5120 Ksym/sec	22800000 Hz	45.5 dBmV
4	Locked	ATDMA	4	5120 Ksym/sec	29200000 Hz	46 dBmV
5	Locked	ATDMA	6	2560 Ksym/sec	40400000 Hz	46.3 dBmV
6	Locked	ATDMA	1	2560 Ksym/sec	10400000 Hz	44.3 dBmV
7	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV
8	Not Locked	Unknown	0	0 Ksym/sec	0 Hz	0.0 dBmV

plemans · ‎2022-05-06

You got the cable connections page but not the event logs.

Are you doing any torrenting? I noticed when I tested one that it struggles with multiple connections from a torrent client. I'd had my torrent client set to 800 connections possible and had the same symptoms. I had to set it down to 200

Relyt · ‎2022-05-06

I posted the events log on Comcast forums and they got flagged due to the MAC address being displayed, was unsure if the same would happen on this forum as well.

I am not torrenting, only basic internet use. I do connect to employers VPN for remote work, which is laggy with regular disconnects.

Time	Priority	Description
1970-1-1, 00:00:49	Notice (6)	Honoring MDD; IP provisioning mode = IPv6
1970-1-1, 00:00:42	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:01:xx:xx:xx:xx;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:40	Notice (6)	WiFi Interface [wl1] set to Channel 161 (Side-Band Channel:N/A) - Reason:INIT
1970-1-1, 00:00:40	Notice (6)	WiFi Interface [wl0] set to Channel 8 (Side-Band Channel:N/A) - Reason:INIT
1970-1-1, 00:00:37	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-5-6, 09:42:45	Critical (3)	Resetting the cable modem due to docsDevResetNow
1970-1-1, 00:00:37	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:44	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:01:xx:xx:xx:xx;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:37	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:45	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:01:xx:xx:xx:xx;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:38	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-5-5, 15:45:39	Critical (3)	Resetting the cable modem due to docsDevResetNow
1970-1-1, 00:00:37	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:45	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:01:xx:xx:xx:xx;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:38	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:44	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:01:xx:xx:xx:xx;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:37	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-5-2, 16:39:14	Critical (3)	Resetting the cable modem due to docsDevResetNow
1970-1-1, 00:00:44	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:01:xx:xx:xx:xx;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:37	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-5-2, 15:58:06	Critical (3)	Resetting the cable modem due to docsDevResetNow
1970-1-1, 00:00:45	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:01:xx:xx:xx:xx;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:38	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-4-28, 16:18:27	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:01:xx:xx:xx:xx;CM-QOS=1.0;CM-VER=3.0;
2022-4-28, 16:18:20	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-4-28, 16:18:18	Critical (3)	No UCDs Received - Timeout;;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
2022-4-28, 16:18:02	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:01:xx:xx:xx:xx;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:01:19	Critical (3)	No Ranging Response received - T3 time-out;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:01:xx:xx:xx:xx;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:01:11	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:01:10	Critical (3)	No UCDs Received - Timeout;;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:53	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:43	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:42	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire FEC framing;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;
1970-1-1, 00:00:39	Critical (3)	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=80:cc:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.0;CM-VER=3.0;

plemans · ‎2022-05-06

Your logs are indicating a line issue thats trigger a reset from the cmts.

If you've already checked all your lines/connections, then the isp would need to check it.

Start with removing any amplifiers, signal attenuators, or splitters from the coax.
From there check the line for kinks, damage, moisture in the line.
Check the connectors for improperly made ends, foil touching the copper coax line, bad/old/cheap connectors, or corroded connections. Replace them if you do.
If you can, simply connect the modem right where the coax comes into the home. This prevents wiring in the home from being the issue. And some ISP’s charge if the wiring issue is in the home. So this helps prevent this.

Relyt · ‎2022-05-06

10-4. I live in an apartment building but I'll try connecting it to the other entry point.

The cable is currently directly connected to the coax, no splitters or amplifiers are connected.

I appreciate you helping out plemans. I wanted to ask someone more knowledgeable before committing to an ISP tech visit and fee vs returning/purchasing a new modem/router.

C7000 v2 inconsistent download speeds - 2.0-300.0 Mbps

C7000 v2 inconsistent download speeds - 2.0-300.0 Mbps

Re: C7000 v2 inconsistent download speeds - 2.0-300.0 Mbps

Re: C7000 v2 inconsistent download speeds - 2.0-300.0 Mbps

Re: C7000 v2 inconsistent download speeds - 2.0-300.0 Mbps

Re: C7000 v2 inconsistent download speeds - 2.0-300.0 Mbps