Hub 3 Modem - High Latency, Dropped Packets, Loss of Sync, T3 Timeouts

[katspike]

I'm using my Hub 3 in Modem mode. It’s been working for several years with no noticeable issues… but for the last week, it started disconnecting around the same time every day. Running tests via the VM website do not reveal any errors. However, my network log shows warnings and critical errors and the Broadband Quality Monitor (BQM) shows high latency and dropped packets.

Every day, the network log shows the following warnings and critical errors between 10 and 12noon, and then at around 4pm. My family uses Internet heavily in the evening, but not as much at midday when it fails. It seems to get worse after each attempt by VM customer service to fix it.

Network Log Summary:

“Critical   - SYNC Timing Synchronization failure - Loss of Sync”

“Warning - RCS Partial Service

"Critical   - No Ranging Response received T3 timeout"

Plus a critical error from 1970 ?!

(See here for an explanation of these errors)

All internet connectivity is lost, and the hub tries to renegotiate channels, sometimes several times a day. The rest of the time, the network is good - even at night when there’s a lot of streaming and gaming activity.

I've read many posts with similar problems, but not many solutions, and everyone's setup is different. I need some help to identify the cause of my issue.  Really appreciate any advice you may have.

Here's a diagram of my setup showing all wired devices:

My Setup: 

• HUB 3.0 (Modem Mode)
• 350M Oomph Plan (broadband, landline, mobile)
• Daytime use: 1-2 adults, W.F.H - video meetings, streaming podcasts, web development
• Night-time use 2 adults, + 2 teens - a mix of video streaming and / or X-box or PS4
• Router is configured as DHCP+NAT
• Daisy-chain: Modem > Router > TP-Link 16 port Gigabit Switch > Cat 5e patch panel > Netgear Gigabit Switches > Airport Express bridge mode wireless networks
• Cat5e / Cat6 ethernet throughout house
• Problem occurs on both Wired and Wireless clients
• Line was installed in 2017

Total Connected (not all used at once):

 20  wired devices  (maximum 12 in concurrent use).
 10  wireless devices
 48  zigbee smart bulbs, sensors, switches and sockets (Hue)

Broadband Quality Monitor (BQM): 

Live Link

Issue:

Some outages are very short, and the frequency of occurrence varies, but it usually fails and reboots itself between 10am and 11am - even though demand is low and not many devices are being used at that time.

 Attempts to rectify: 

• VM have run several tests remotely and on-site
• VM Engineer removed old Tivo splitter and replaced connections - he only considered the Hub - he did not visually inspected anything connected to it, including the coax cable that runs up the side of the house. I live right on the coast where salt-water corrosion is a major issue.
• Confirmed all connections are tight
• VM Engineer saw my BQM, but did not look at network logs
• The modem and router are fan-cooled but temperature can still reach 30 deg C.
• Power Off / On Modem for 5 mins 
• Power off all devices several hours
• Reset Modem
• Disconnected all connected equipment and changed to Router mode
• VM changed frequency and increased something (they weren’t specific)
• Reduced the amount of devices connecting to the network - just 2 mobiles, 1 laptop and Apple TV - still failed
• Increased cooling
• Another engineer is booked

Possible Correlation:

The problem seemed to start around the same time that I added a PoE wireless outdoor AP (Access Point). But when I disconnected the AP it still failed, so I don’t think it’s the cause.

Around this time my neighbour also got Virgin Media installed, but VM say that is not related (I remain sceptical).

The large green junction cabinet on the street nearby has a door that keeps falling off. I have booked an engineer to fix via 0330 333 0444

[Steven_L]

Thanks for the update @katspike.

How did the visit go for you, has the technician been able to resolve your connection issues?

Regards,

Steven_L

[katspike]

Hi Steven_L, thanks for checking.

I'm seeing the same critical errors in the network log, and it was especially bad the day *after* the engineer's visit.... but the connection hasn't actually dropped today yet (first time in two weeks).

This time, the engineer visited during the time of day when the connection is usually bad, but he couldn't detect any signal issues, but it does seem to be quite sporadic. However, he moved my position in the street cabinet again, replaced the power supply for the hub and moved it away from the coax cable.

When the connection failed roughly 12hrs after the engineer visit, I decided to replace the electrical socket and remove one of the cooling fans (a laptop cooler purchased in September). The connection has been more stable since removing the fan - maybe a coincidence.

I would not say it's completely fixed (see errors in next post > network log)... the engineer said it's very difficult to get the balance right when a property is situated right next to a cabinet... so maybe this is as good it gets? 

People keep mentioning "postRS errors" does this mean errors after resetting the hub? Perhaps I should try that again? 

[katspike]

Network Log (3 days after third engineer visit)

Time	Priority	Description
09/11/2021 12:14:28	critical	No Ranging Response received - T3 time-out;
08/11/2021 09:33:56	Warning!	RCS Partial Service;
08/11/2021 09:33:22	critical	No Ranging Response received - T3 time-out;
08/11/2021 09:33:17	Warning!	RCS Partial Service;
08/11/2021 09:33:17	critical	SYNC Timing Synchronization failure - Loss of Sync;
08/11/2021 09:04:18	Warning!	RCS Partial Service;
08/11/2021 09:04:15	critical	No Ranging Response received - T3 time-out;
08/11/2021 09:04:2	Warning!	RCS Partial Service;
08/11/2021 08:53:32	critical	Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;
08/11/2021 08:49:13	critical	No Ranging Response received - T3 time-out;
08/11/2021 08:47:52	Warning!	RCS Partial Service;
08/11/2021 08:47:14	critical	No Ranging Response received - T3 time-out;
08/11/2021 08:47:14	Warning!	RCS Partial Service;
08/11/2021 08:47:9	critical	Unicast Maintenance Ranging attempted - No response - Retries exhausted;
08/11/2021 08:47:9	critical	Ranging Request Retries exhausted;
08/11/2021 08:46:25	critical	No Ranging Response received - T3 time-out;
08/11/2021 08:03:51	Warning!	RCS Partial Service;
08/11/2021 08:02:39	critical	No Ranging Response received - T3 time-out;
08/11/2021 07:51:40	Warning!	RCS Partial Service;
08/11/2021 07:50:47	critical	No Ranging Response received - T3 time-out;

 

Upstream bonded channels

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

1	53700000	46.5	5120	64 qam	1
2	46200000	46.3	5120	64 qam	2
3	32600015	45.5	5120	64 qam	4
4	39400059	45.8	5120	64 qam	3

Upstream bonded channels

Channel Channel Type T1 Timeouts T2 Timeouts T3 Timeouts T4 Timeouts

1	ATDMA	0	0	0	0
2	ATDMA	0	0	62	0
3	ATDMA	0	0	64	0
4	ATDMA	0	0	64	0

 

[katspike]

Downstream bonded channels

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

1	202750000	5.3	40	256 qam	9
2	138750000	4.6	40	256 qam	1
3	146750000	4.5	40	256 qam	2
4	154750000	4.8	40	256 qam	3
5	162750000	5	40	256 qam	4
6	170750000	5.3	40	256 qam	5
7	178750000	5.3	40	256 qam	6
8	186750000	5.4	40	256 qam	7
9	194750000	5.5	40	256 qam	8
10	210750000	5.1	40	256 qam	10
11	218750000	5.4	40	256 qam	11
12	226750000	5.4	40	256 qam	12
13	234750000	5.3	40	256 qam	13
14	242750000	4.9	40	256 qam	14
15	250750000	4.5	40	256 qam	15
16	258750000	4.5	40	256 qam	16
17	266750000	4.5	40	256 qam	17
18	274750000	4.5	40	256 qam	18
19	282750000	4.9	40	256 qam	19
20	290750000	5.1	40	256 qam	20
21	298750000	5.5	40	256 qam	21
22	306750000	5.5	40	256 qam	22
23	314750000	5.6	40	256 qam	23
24	322750000	6	40	256 qam	24

 

Downstream Bonded Channels

Channel	Locked Status	RxMER (dB)	Pre RS Errors	Post RS Errors
1	Locked	40.9	33012	12528
2	Locked	40.3	501798	260197
3	Locked	40.3	250376	78019
4	Locked	40.9	291212	68146
5	Locked	40.9	333047	120139
6	Locked	40.9	43196	15853
7	Locked	40.3	35267	13902
8	Locked	40.9	35328	13315
9	Locked	40.3	34523	13073
10	Locked	40.9	33935	11651
11	Locked	40.9	33799	11364
12	Locked	40.3	34205	12833
13	Locked	40.3	33539	12720
14	Locked	40.3	31261	10360
15	Locked	40.3	30979	10045
16	Locked	40.9	31028	9975
17	Locked	40.9	33631	10779
18	Locked	40.9	31329	10191
19	Locked	40.9	28560	7405
20	Locked	40.3	27283	5842
21	Locked	40.3	26251	4775
22	Locked	40.9	25467	4184
23	Locked	40.3	25962	4397
24	Locked	40.9	25836	4437

[katspike]

What is the meaning of "PostRS errors". Are they errors after Re-Setting the hub?

[katspike]

Is anyone still monitoring this thread? I am still experiencing problems after booking four engineers, so I was hoping someone on the forum might be able to identify something that the engineers and VM customer support team have missed.

Can someone at least answer this simple question about the network log: 

What is the meaning of "Post RS errors". Are they errors after Re-Setting the hub?

I assume 120139 post RS errors is bad, but no-one has been able to explain what that actually means.

[risc19]

They are errors that’s the hub could not correct. 

They are not good and are not a sign of a healthy connection.  

However they are cumulative so they may have been from when the engineer was fiddling around with the connection. 

Restart the hub, this will reset them to 0. 
Wait 24 hours and repost the numbers here.

If you have any within 24 hours and/or timeouts it’s not fixed.  

[katspike]

Thanks, I've reset it now, and will monitor carefully.

[Adduxi]

---

@katspike wrote:

What is the meaning of "PostRS errors". Are they errors after Re-Setting the hub?

---

Read this sticky Hub status data - understanding network log messag... - Virgin Media Community - 4716616  Very worth while.

Thanks to @Andrew-G  for taking the time to post it up.

[Akua_A]

Thank you for the update @katspike.

Just to confirm how has service been since the reboot? Do you need any further help?

Thanks,