Intermittent slow speeds (~0.5Mbps) for 30s, Modem Mode, Normally 300Mbps+

[XDGFX]

Hi all,

I've seen similar posts to this one before, but they all either end without resolution, or after a VM member starts a private chat with the OP.

I get intermittent slow speeds on my VM 350 connection. Some days this will happen every 5-10 minutes, dropping the speed down to ~0.5Mbps, before returning back to ~full speed. Some days are without issue.

This happens on wired connections as well as WiFi.

I'm using Modem Mode, the router is an EdgeRouter X. Speedtests on the ER also show the same slowdown, so I'm fairly confident it's the VM hub.

As suggested in other threads I've set up a Broadband Quality Monitor here. So far it shows nothing too unexpected.

I have been getting critical errors in the VM hub network log (note MAC addresses have been redacted):

Time	Priority	Description
05/07/2021 16:58:16	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
05/07/2021 16:46:17	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
05/07/2021 10:49:29	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
05/07/2021 08:32:43	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
05/07/2021 08:23:39	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
05/07/2021 08:04:22	notice	LAN login Success;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
05/07/2021 08:04:14	Warning!	LAN login FAILED : Incorrect Username / Password / ConnectionType;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
04/07/2021 12:27:28	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
04/07/2021 10:46:6	critical	SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:51:40	Warning!	RCS Partial Service;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:37:55	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:37:31	critical	Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:37:31	critical	Ranging Request Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:31:6	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:30:42	critical	Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:30:42	critical	Ranging Request Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:24:18	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:23:54	critical	Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:23:54	critical	Ranging Request Retries exhausted;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;
03/07/2021 10:17:29	critical	No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.0;

Most notably No Ranging Response received and SYNC Timing Synchronization failure

Upstream and downstream bonded channels are shown below, I'm not sure if these indicate an issue but each channel looks relatively consistent at least.

Downstream bonded channels
Channel	Frequency (Hz)	Power (dBmV)	SNR (dB)	Modulation	Channel ID
1	474250000	8	38	256 qam	9
2	410250000	9.6	38	256 qam	1
3	418250000	9.3	38	256 qam	2
4	426250000	8.9	40	256 qam	3
5	434250000	8.5	38	256 qam	4
6	442250000	8.3	40	256 qam	5
7	450250000	8	38	256 qam	6
8	458250000	7.9	38	256 qam	7
9	466250000	7.9	38	256 qam	8
10	482250000	8.1	38	256 qam	10
11	490250000	8	38	256 qam	11
12	498250000	7.8	38	256 qam	12
13	506250000	7.5	38	256 qam	13
14	514250000	7.5	38	256 qam	14
15	522250000	7.8	38	256 qam	15
16	530250000	7.5	38	256 qam	16
17	538250000	7	38	256 qam	17
18	546250000	6.6	38	256 qam	18
19	554250000	6.6	38	256 qam	19
20	562250000	6.8	38	256 qam	20
21	570250000	7	38	256 qam	21
22	578250000	6.6	38	256 qam	22
23	586250000	6.4	38	256 qam	23
24	594250000	6.5	38	256 qam	24


Downstream bonded channels
Channel	Locked Status	RxMER (dB)	Pre RS Errors	Post RS Errors
1	Locked	38.9	771	789
2	Locked	38.9	2346	452
3	Locked	39.3	2215	469
4	Locked	40.3	2000	522
5	Locked	38.9	2040	703
6	Locked	40.3	1805	712
7	Locked	38.9	1656	798
8	Locked	38.9	1338	875
9	Locked	38.9	991	1035
10	Locked	38.9	587	586
11	Locked	38.9	543	485
12	Locked	38.9	483	601
13	Locked	38.9	337	348
14	Locked	38.9	286	143
15	Locked	38.9	295	27
16	Locked	38.6	256	6
17	Locked	38.6	307	0
18	Locked	38.9	444	4
19	Locked	38.6	508	20
20	Locked	38.9	558	30
21	Locked	38.9	553	15
22	Locked	38.9	511	52
23	Locked	38.9	494	42
24	Locked	38.6	465	33


Upstream bonded channels
Channel	Frequency (Hz)	Power (dBmV)	Symbol Rate (ksps)	Modulation	Channel ID
1	39400000	39.2	5120	16 qam	2
2	25800024	32.5	5120	16 qam	4
3	32600380	33.2	5120	16 qam	3
4	46200000	35	5120	16 qam	1


Upstream bonded channels
Channel	Channel Type	T1 Timeouts	T2 Timeouts	T3 Timeouts	T4 Timeouts
1	ATDMA	0	0	0	0
2	ATDMA	0	0	2	0
3	ATDMA	0	0	0	0
4	ATDMA	0	0	0	0

Any suggestions on fixing this issue?

[XDGFX]

Yes, Hub 3.

[Zak_M]

Good afternoon @XDGFX, 

I have taken a further look over your account & there is an SNR outage that is affecting the area. This is due to be resolved on the 11/10/21 however with SNR issue they are notoriously difficult to locate and resolve so this might still be pushed back. 

Kind regards,

Zak_M

[XDGFX]

I get the impression that new replies are being made without reading the previous messages in this topic...

For now I will ignore VM requests to return the faulty hub, unless I get further prompts.

Also, I've no idea what happened on the 5th October at about 11am but my latency dropped incredibly, and has since remained quite low.

I will assume the issue has been fixed by replacing the VM router, and so this issue can be considered closed. I will re-open if the issue develops again.

[legacy1]

Yes that BQM is low for a Docsis connection are you sure you got the right IP for BQM?

In the hub Operation Configuration for Primary Upstream Service Flow what does the Scheduling Type show as?

[Chris_W1]

Hi XDGFX, thanks for the message. I am sorry to hear that you were having issues with the connection and am glad to hear that the issue is now resolved. Please keep an eye on the connection and let us know if anything changes? - Chris.