Frequent disconnections - BT Home Hub 5

[#1]

Morning, John.

The miserable speed test results may well be a member of my family optimistically expecting OneDrive to work as a backup. When said person returns from a Saturday bike ride I shall ask!

The latest I have from PlusNet is from 24 February. Here it is.

Plusnet Support - CSC Analyst

4:59pm, Wednesday 24 Feb 2021

Dear [Redacted],
WP Product: WBC MAX24 mb/s (ADSL2+ Annex A) Uncapped Upstream
WP Profile: Generic Speed 12300 No Time Out Change
Ellacoya: Service_Offer_59

---

Connected for null
14 drops in last 24 hours
14 drops in last 72 hours

KBD

BRAS		Profile Info	WBC 160K - 24M Low delay (INP 0) 9dB Downstream, UC Medium delay (INP 2) 6dB Upstream (ADSL2+)
Use Self Service Repair to perform port flex. If further assistance is required please report the fault into BTW.

xDSL

Status

Circuit In Sync

	Upstream	Downstream
Loop loss	8.8	16.5
SNR Margin	11.3	20.6
Errored Seconds	1	1
HEC Errors	0
Speed	864	15348

Maximum Stable Rate	21568	Fault Threshold Rate	17254
MTBR	86400	ILQ	C
MTBE (Downstream)	480	MTBE (Upstream)	160

Summary

MGALS Value: 6.5 Mbps

• High number of drops, possible DCN issue

• Workplace profile was mismatched and has been updated

• No BT Wholesale speedtest has been performed on this connection

...and here is the current router "Helpdesk" stuff. I disconnected and re-booted the router half an hour before, and it's given a higher speed and smaller noise margin than yesterday. (The router's not providing Wi-Fi -- that's done from an access point upstairs on a wired connetion.)

1. Product name:	BT Home Hub
3. Firmware version:	Software version 4.7.5.1.83.8.264 (Type A) Last updated 05/03/19
4. Board version:	BT Hub 5A
5. DSL uptime:	0 days, 00:33:16
6. Data rate:	1033 / 22751
7. Maximum data rate:	1032 / 22856
8. Noise margin:	7.1 / 9.1
9. Line attenuation:	8.7 / 15.8
10. Signal attenuation:	8.7 / 15.0
11. Data sent/received:	149.9 MB / 197.4 MB
19. 5 GHz Wireless connections:	Disabled
22. Firewall:	Default
23. MAC Address:	d0:84:b0:ec:08:82
24. VPI/VCI:	0 / 38
25. Modulation:	G.992.5 Annex A
26. Latency type:	Interleaved
27. Software variant:	AA
28. Boot loader:	1.0.0

and here are some snippets from the WAN part of the router log, yesterday evening.

21:06:46, 26 Feb.	(199394.260000) PPP LCP Receive Configuration Reject
21:06:46, 26 Feb.	(199394.090000) PPP LCP Send Configuration Request
21:06:38, 26 Feb.	(199385.950000) ETHoA is up -​ VPI: 0, VCI: 35 Down Rate=18284Kbps, Up Rate=963Kbps; SNR Margin Down=12.9dB, Up=8.2dB
21:06:38, 26 Feb.	(199385.950000) ATM over DSL is up
21:06:10, 26 Feb.	(199358.470000) ATM over DSL is down after 172 minutes uptime
21:06:10, 26 Feb.	(199358.470000) ETHoA is down after 172 minutes uptime
21:06:10, 26 Feb.	(199358.460000) PPPoA is down after 171 minutes uptime [Waiting for Underlying Connection (WAN ATM over DSL -​ Down)]
21:06:08, 26 Feb.	(199355.580000) PPP LCP Send Termination Request [User request]
18:14:20, 26 Feb.	(189047.690000) WAN operating mode is ADSL

and the disconnection before that...

18:13:55, 26 Feb.	(189022.960000) ETHoA is up -​ VPI: 0, VCI: 35 Down Rate=20620Kbps, Up Rate=1002Kbps; SNR Margin Down=7.7dB, Up=7.6dB
18:13:55, 26 Feb.	(189022.960000) ATM over DSL is up
18:12:58, 26 Feb.	(188966.450000) ATM over DSL is down after 1933 minutes uptime
18:12:58, 26 Feb.	(188966.450000) ETHoA is down after 1933 minutes uptime
18:12:58, 26 Feb.	(188966.450000) PPPoA is down after 1932 minutes uptime [Waiting for Underlying Connection (WAN ATM over DSL -​ Down)]
18:12:55, 26 Feb.	(188963.300000) PPP LCP Send Termination Request [User request]
10:00:23, 25 Feb.	(73014.560000) WAN operating mode is ADSL

Then an RS noise plot for the evening. (click to embiggen?) That shows more drops than the router log, although I do remember seeing the pesky connection light flashing away several times, whenever the data flow was frozen and more or less matching the other drops in the noise margin.

 What I need now is a bit of PlusNet technical support or Openreach engineering to find and fix it. Oh well.

 - Mark

[#2]

Hi Mark - note to you family member: back-ups should ideally be made to local media, a largish external HDD isn't that expensive.

The KBD report looks a bit ugly, but your current Helpdesk shot looks much better - wonder if they've actually done the port flex?

You RS plot is a little disturbing, though - it should be MUCH flatter than that, and I don't understand the frequent falls to zero, with an almost instantaneous recovery, nor the change in D/S margins over such a short period. If I didn't know better, I would suspect network issues between you and the exchange.

The situation certainly need further BTOR investigation.

[#3]

PlusNet support phoned back today! BT Openreach engineer booked for Wednesday afternoon. Let's hope it's going wrong (i.e. exhibiting symptoms) at the time, so that the fault can be positively identified. (Once one gets to speak to a PlusNet staff member, they are (all) very helpful. Just seems to take a long time to get to the head of the queue of support cases.)

 - Mark

[#4]

I think the spiky drops to zero of the naise margin in the RouterStats plots are symptoms of a weakness in the the way RS has to get its data samples from the Home Hub 5/PlusNet One. It scrapes a refreshed copy of the router's "Helpdesk" web page; I think that now and again the page refresh doesn't work quite right.

It looks even more alarming at this moment, because (I think as the immediate effect of some line adjustments done from PlusNet yesterday) the router sometimes reports a remarkable number for noise margin:-

8. Noise margin: 429496729.4 / 8.4

That's a lot of decibels (a signal powerful enough to create an entire universe, or at least run a few galaxies), but I recognise the number as just under 2^32 ÷ 10. It's been calculating in 0.1 dB units using unsigned 32-bit integer arithmetic, and has underflowed. I conclude that is just an insignificant bug in the router's reporting software.

 - Mark

[#5]

OK Mark, I'll take your word on the spikes - I've never used a HH5/PN1 as I had a Netgear DG834G for many years (lovely piece of kit), and when that got tired, switched to a TG582N which has served me well, but neither of those exhibited that kind of behaviour unless I hit a network problem.

Interesting/scary SNR, btw.

[#6]

This message is to update the story after the Openreach engineer visited on Wednesday afternoon. He could not find any fault whatsoever, but (of course) carried out a lot of tests and reset some of the connection's settings. We disconnected the router completely (from ADSL, wired Ethernet and power), he looked at it, said it might possibly be faulty and left me with a used BT Home Hub 4 fished out of the back of his van to try as a substitute. He identified some faint fizzing noises on the telephone line as broadband signal being not completely isolated by the filters in the faceplate of the master socket.

I determined the correct action next should be

(a) Reconnect my HH5 router, give it up to a week to find out whether I was still getting disconnections.

(b) If still problems, try a week with the substitute HH4...

If (a) OK, whatever was wrong is fixed; if (b) OK, I need a new router; if (b) still not OK, there's a line fault remaining.

The connection has been steady, no problems, faster than ever before at 23.3 Mbps down, 1.19 Mbps up, and 5.1--6.0 dB noise margin on both, for just over 3 days now. That's less than half way through test (a) but looking hopeful.

One oddity makes me suspect a firmware error in the HH5 router. Previously I had (when trying to troubleshoot) left the router powered on, and rebooted it from its Web control panel. This time, after powering it off and on again, it's showing a steady amber Wi-Fi light, which the instruction book tells me means that my Wi-Fi network is insecure. It wasn't showing that before: and Wi-Fi is disabled completely, so ought to be reasonably secure. This paragraph probably belongs in a different bulletin board, though.

Then today I got a phone call from Bob in PlusNet support, following up from Wednesday's Openreach visit. (The Bob? I didn't ask.) As previously for communications with PlusNet, very helpful, but clearly there is a rather long queue of support calls or tickets.

 - Mark

[#7]

HI Mark. That sounds a little more hopeful. I assume from your comments re the faceplate that you have a 5C master socket/Mk.4 faceplate set-up, if so the faceplates are cheap enough to replace - IF the internal filter is dodgy.

Out of interest, can you post the router stats page, and the current RSHH5 log?

As you aren't using Wi-Fi, it should be safe to ignore the amber light.

Post back if you get any more interesting action. Is your phone-line now clear?

[#8]

Yes, I have a Master Socket 5C with MK.4 faceplate. The connection has lasted a full week without drops or glitches (until a short power cut in this morning's wind storm, which had the expected effect on the mains-powered router). Here is an example (very boring) noise margin graph from a few days back: click for details. Here also are the variable parts of the Home Hub 5's "Helpdesk" page from a few minutes ago: it's reconnected at what still seems a very impressive speed.

The BT engineer commented that his checking equipment reports the phone line as 750 metres or so to the exchange. Apparently it goes the wrong way up the street to a junction box, then back to the exchange, more than doubling the distance compared with the route one would take on foot.

5. DSL uptime:	0 days, 00:35:22
6. Data rate:	1139 / 23521
7. Maximum data rate:	1140 / 23648
8. Noise margin:	7.0 / 5.2
9. Line attenuation:	8.7 / 16.5
10. Signal attenuation:	8.6 / 15.6
11. Data sent/received:	231.8 MB / 318.5 MB

24. VPI/VCI:	0 / 38
25. Modulation:	G.992.5 Annex A
26. Latency type:	Fast

Thank you for the help and advice!

 - Mark

[#9]

Fingers crossed it stays that way, Mark 😁

Just out of interest, my phone line has a couple of 'extra' loops - straight up the main road, slight right to the cabinet, back on itself to rejoin the main road, left down the road above me to the local underground DP, and then overhead from there to me - probably adding 80-100m to its length.