Poor upload speeds - under 1 Mbps on VM Hub 5 Router

[ozzy3]

Hi,

We've been experiencing very poor upload speeds (under 1 Mbps) on the VM Hub 5 Router when I should be getting between 48-52 Mbps for the 1 gig tariff, download speed seems to be good (around 757 Mbps) - these figures are based on SamKnows RealSpeed test - the download speed going to the router is 1 Gbps whilst the upload speed is 0.3 Mbps whilst the download speed from the router to the laptop is 757 Mpbs whilst the upload speed remains low. This has been going on for the past couple of weeks causing issues with regards to working from home.

I have reset the router a couple of times and rebooted it a few times, checked all cables are tight, etc. I called VM and they told me that there's an outage but I don't understand how an outage can cause the upload speed to be extremely low but the download speed to remain fine.

I'll post the router status in the next posts to see if someone can identify what the issues might be.

[ozzy3]

Cable Modem StatusItem Status Comments

Acquired Downstream Channel(Hz)	306000000	Locked
Ranged Upstream Channel(Hz)	49600000	Ranged
Provisioning State	Online	Operational

Downstream bonded channels

Channel Frequency (Hz) Power (dBmV) SNR (dB) Modulation Channel ID

1	306000000	6.7	39	QAM 256	22
2	138000000	7.9	39	QAM 256	1
3	146000000	7.9	39	QAM 256	2
4	154000000	7.6	39	QAM 256	3
5	162000000	7.3	39	QAM 256	4
6	170000000	6.7	39	QAM 256	5
7	178000000	6.4	39	QAM 256	6
8	186000000	6.2	39	QAM 256	7
9	194000000	6.6	39	QAM 256	8
10	202000000	6.5	39	QAM 256	9
11	210000000	6.8	39	QAM 256	10
12	218000000	6.6	39	QAM 256	11
13	226000000	6.2	39	QAM 256	12
14	234000000	5.9	39	QAM 256	13
15	242000000	5.7	39	QAM 256	14
16	250000000	5.6	39	QAM 256	15
17	258000000	6	39	QAM 256	16
18	266000000	5.7	39	QAM 256	17
19	274000000	5.6	39	QAM 256	18
20	282000000	5.7	39	QAM 256	19
21	290000000	6	39	QAM 256	20
22	298000000	6.3	39	QAM 256	21
23	314000000	6.8	39	QAM 256	23
24	322000000	6.7	39	QAM 256	24
25	330000000	6.6	39	QAM 256	25
26	338000000	6.6	38	QAM 256	26
27	346000000	6.4	38	QAM 256	27
28	354000000	5.7	38	QAM 256	28
29	362000000	5.3	38	QAM 256	29
30	370000000	5	38	QAM 256	30
31	378000000	4.8	38	QAM 256	31

Downstream bonded channels

Channel Locked Status RxMER (dB) Pre RS Errors Post RS Errors

1	Locked	39	0	0
2	Locked	39	0	0
3	Locked	39	0	0
4	Locked	39	0	0
5	Locked	39	0	0
6	Locked	39	0	0
7	Locked	39	0	0
8	Locked	39	0	0
9	Locked	39	0	0
10	Locked	39	0	0
11	Locked	39	0	0
12	Locked	39	0	0
13	Locked	39	0	0
14	Locked	39	0	0
15	Locked	39	0	0
16	Locked	39	0	0
17	Locked	39	0	0
18	Locked	39	0	0
19	Locked	39	0	0
20	Locked	39	0	0
21	Locked	39	0	0
22	Locked	39	0	0
23	Locked	39	0	0
24	Locked	39	0	0
25	Locked	39	0	0
26	Locked	38	0	0
27	Locked	38	0	0
28	Locked	38	0	0
29	Locked	38	0	0
30	Locked	38	0	0
31	Locked	38	0	0

Upstream bonded channels

Channel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID

0	49600000	29.5	5120	QAM 16	1
1	43100000	28.3	5120	QAM 16	2
2	36600000	26.8	5120	QAM 16	3
3	30100000	27	5120	QAM 16	4
4	23600000	27.8	5120	QAM 16	9

Upstream bonded channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

0	ATDMA	0	0	0	0
1	ATDMA	0	0	9	0
2	ATDMA	0	0	2	0
3	ATDMA	0	0	0	0
4	ATDMA	0	0	0	0

[ozzy3]

General Configuration

Network access Allowed
Maximum Number of CPEs 1
Baseline Privacy Enabled
DOCSIS Mode 3.1
Config file cmreg-vmdg660-bbt076-b.cm
Primary Downstream Service Flow

SFID 63600
Max Traffic Rate 1230000450 bps
Max Traffic Burst 42600bytes
Min Traffic Rate 0 bps

Primary Upstream Service Flow

SFID 63599
Max Traffic Rate 55000270 bps
Max Traffic Burst 42600bytes
Min Traffic Rate 0 bps
Max Concatenated Burst 42600bytes
Scheduling Type Best Effort

Network Log

Time Priority Description

13-01-2023 18:37:37	critical	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
13-01-2023 18:36:23	notice	REGISTRATION COMPLETE - Waiting for Operational status
13-01-2023 18:36:19	critical	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
13-01-2023 18:36:16	notice	US profile assignment change. US Chan ID: 10; Previous Profile: 13; New Profile: 12 13.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
13-01-2023 18:36:11	notice	DS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3.;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
13-01-2023 18:35:58	warning	DHCP WARNING - Non-critical field invalid in response ;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
13-01-2023 18:35:56	notice	Honoring MDD; IP provisioning mode = IPv4
13-01-2023 18:35:44	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
13-01-2023 18:35:33	critical	Cable Modem Reboot due to power button reset
12-01-2023 12:46:21	critical	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
12-01-2023 12:45:44	critical	Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
12-01-2023 12:44:55	critical	Started Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
12-01-2023 12:44:49	critical	SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.1;CM-VER=3.1;
12-01-2023 12:44:37	critical	Cable Modem do Reboot Factory reset UI

[Client62 · Accepted solution]

The fault on the upstream looks to be as described.

The Upstream channels are impacted, this group of 5 are all at QAM 16 the slowest rate,  QAM 64 for all 5 is the normal mode.

Regarding how Downstream is fine but Upstream is not, the two directions use different frequencies,
damage to a cable in the local area can result in a degraded performance
on either or both the Upstream and Downstream.

[carl_pearce]

Upstream bonded channels

Channel Frequency (Hz) Power (dBmV) Symbol Rate (ksps) Modulation Channel ID

0	49600000	29.5	5120	QAM 16	1
1	43100000	28.3	5120	QAM 16	2
2	36600000	26.8	5120	QAM 16	3
3	30100000	27	5120	QAM 16	4
4	23600000	27.8	5120	QAM 16	9

---

Your upstream channels are out of spec on QAM, which should be 64 on all channels. QAM is the equivalent of bandwidth so it explains the slow upload speed.

Edit: beat me to it...

[Tudor]

Check with Area faults on 0800 561 0061 If you have a VM landline 150 this goes down to post code level. You could also try the web page status, but this is not recommended as it only covers issues that affect a very large number of customers.

VM will not dispatch any technicians while an area fault exists.

If no area faults found:

The primary place to report faults or for service requests is Customer Services on 0345 454 1111/150 if you have a VM landline or wait two or three days for a VM staff member to get to your post.

[ozzy3]

Thank you very much for your response Client62, it makes sense.

I was told that there's an area fault which is affecting the upload speeds and should be resolved tomorrow (17th January).

Many thanks to everyone else who has responded to my post.

[Matthew_ML]

Hey ozzy3, thank you for reaching out and a warm welcome to the community I am sorry to see you are having some connection issues.

I have taken a look and I can see from our side there is an SNR outage lasting until the 31st January 2023.

I am sorry about any trouble this may cause can you keep an eye on any updates here. Thanks