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BT Hub woes - really weird - thought I would share.

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stduc

stduc

Programmer
Nov 26, 2002
1,903
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Broadband access at my Dad's has never been good. He's at the end of nearly 7 miles of copper. However. recently BT supplied him with a Home Hub 3 and brought fibre to within a mile or so. Speed went up initially to around 2Mb and then 3.5 and then suddenly the connection became very unreliable. Rarely lasting more than a day and demanding the hub was off overnight to re-establish a connection.

His network consists of various windows 7 laptops and notebooks connecting using wifi and 1 oldish but still serviceable XP machine that is connected via ethernet cable.

After much pondering, experimenting and BT supplying a replacement Hub I have made the following discoveries.

1. After switching off overnight then a reliable connection will be made providing the old XP machine is OFF the speed will start at 3.5Mb and fall off to 1.8Mb at some point where it remains stable.

2. If you power up the XP machine and hold it at the BIOS screen then there are no additional problems.

3. If you allow the XP machine to boot up then in the next 1 second to 1 hour the BT Hub will freeze and the connection is dropped. The Hub will not reconnect unless powered off for at least an hour, preferably overnight. If you use a different hub then you will get a connection but it will be sub 100Kb

4. The replacement Hub makes a faster and more reliable connection of around 1Mb after the XP machine has messed with it!

5. If you connect one of the Windows 7 laptops to the ethernet cable this DOES NOT cause the BT Hub to hang.

So I have I believe eliminated all but this particular machine as being the problem. I have returned the old hub to BT as the new one seems to be a little better and I have fitted the XP machine with a wifi USB dongle so that it can connect that way. So far without problems.

The XP machine is up to date and all drivers are up to date.

Has anyone experienced anything like this? Does anyone have any ideas as to what might have been going on?
 
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Haven't got a BT hub here, so can't lead you through it, but try and check the SNR of the Downstream signal from within the hub. It sounds to me like you have electrical noise being introduced into your network when the XP machine is attached using Ethernet cable. I have see this before, and upon replacing the computer's PSU, the problem vanished. You may also be able to detect extra electrical interference from the XP machine using a small battery portable radio tuned to the medium wave band.

Roger - G0AOZ.
 
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Not a bad idea Roger - I'll have a delve at the screens on the Hub - but they are not exactly Netgears - LOL so I suspect no SNR reports.

However - the plot thickens. After working for several hours the Hub hung using only WiFi. Again - only if the XP machine was connected (via WiFi - NOT if WiFi on and NOT connected). My next brainwave is to try it using the OpenZone connection the Hub offers. I'll report back. If that works I really will be flumoxed. Do BT Hubs not work with XP? ROFL - Of course, that way he won't see the shared printer.
 
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Found it

ADSL Line Status

Connection Information

Line state: Connected
Connection time: 0 days, 02:43:50
Downstream: 2.217 Mbps
Upstream: 832.5 Kbps

ADSL Settings

VPI/VCI: 0/38
Type: PPPoA
Modulation: G.992.3 Annex A
Latency type: Interleaved
Noise margin (Down/Up): 6.6 dB / 7.1 dB
Line attenuation (Down/Up): 57.2 dB / 34.4 dB
Output power (Down/Up): 16.3 dBm / 12.6 dBm
FEC Events (Down/Up): 8053 / 968
CRC Events (Down/Up): 10 / 80
Click to expand...
 
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Figures with THAT XP machine booted & connected via Openzone

Line state: Connected
Connection time: 0 days, 04:09:19
Downstream: 2.217 Mbps
Upstream: 832.5 Kbps

ADSL Settings

VPI/VCI: 0/38
Type: PPPoA
Modulation: G.992.3 Annex A
Latency type: Interleaved
Noise margin (Down/Up): 4.4 dB / 4.3 dB
Line attenuation (Down/Up): 57.2 dB / 34.4 dB
Output power (Down/Up): 16.3 dBm / 12.6 dBm
FEC Events (Down/Up): 75010 / 1051
CRC Events (Down/Up): 14 / 106
Click to expand...

I am not risking a direct connection as the Hub takes several hours to reconnect after it hangs. Connection via Openzone seems OK - but time will tell.
 
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Time told - about 30 minutes after posting the above broadband was lost.

Status after BB went down.

ADSL Line Status

Connection Information

Line state: Connected
Data Transmitted/Received (GB): 0.0 / 0.1
Downstream: 2.217 Mbps
Upstream: 832.5 Kbps

ADSL Settings

VPI/VCI: 0/38
Type: PPPoA
Modulation: G.992.3 Annex A
Latency type: Interleaved
Noise margin (Down/Up): 3.0 dB / 6.7 dB
Line attenuation (Down/Up): 57.2 dB / 34.4 dB
Output power (Down/Up): 16.3 dBm / 12.6 dBm
FEC Events (Down/Up): 13426916 / 1088
CRC Events (Down/Up): 20155 / 106
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
HEC Events (Down/Up): 175293 / 82
Error Seconds (Local/Remote): 524 / 69
Click to expand...

So although the Broadband indicator was steady red it 'thought' it was connected so didn't attempt a reconnect. After pressing the restart button the Broadband indicator flashed red for a bit and then went to steady red.

ADSL Line Status

Connection Information

Line state: Disconnected
Data Transmitted/Received (GB): Not available
Downstream: Not available
Upstream: Not available

ADSL Settings

VPI/VCI: 0/38
Type: PPPoA
Modulation: Not available
Latency type: Not available
Noise margin (Down/Up): Not available
Line attenuation (Down/Up): Not available
Output power (Down/Up): Not available
FEC Events (Down/Up): Not available
CRC Events (Down/Up): Not available
Loss of Framing (Local/Remote): Not available
Loss of Signal (Local/Remote): Not available
Loss of Power (Local/Remote): Not available
HEC Events (Down/Up): Not available
Error Seconds (Local/Remote): Not available
Click to expand...

So I powered it off and went to bed. The next morning it powered up normally. The broadband indicator flashing red for a bit before going blue.
ADSL Line Status

Connection Information

Line state: Connected
Connection time: 0 days, 00:21:36
Downstream: 2.217 Mbps
Upstream: 858 Kbps

ADSL Settings

VPI/VCI: 0/38
Type: PPPoA
Modulation: G.992.3 Annex A
Latency type: Interleaved
Noise margin (Down/Up): 7.4 dB / 5.0 dB
Line attenuation (Down/Up): 56.8 dB / 34.3 dB
Output power (Down/Up): 16.2 dBm / 12.7 dBm
FEC Events (Down/Up): 4141 / 122
CRC Events (Down/Up): 11 / 1
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
HEC Events (Down/Up): 114 / 1
Error Seconds (Local/Remote): 2 / 1
Click to expand...


I had a thought as I drifted off, why not try a bootable CD such as Ubuntu or OpenSuse and see if the Hub still crashes. (sad person aren't I?). So that is the plan for this evening. Visit here later to see the result! LOL
 
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Well having been fine all day on booting Dads XP PC using OpenSUSE - after 30 mins connected via ethernet, broadband was lost. The Hub accepted a reset and reconnected (but slower) so tried wifi - much the same - it wouldn't even connect before broadband went.

So what have I achieved - I've slowed our broadband down from 3.5Mb to 1.2Mb and learnt that this PC is off to the recycle centre.

Current stats
Line state: Connected
Connection time: 0 days, 00:47:00
Downstream: 1.484 Mbps
Upstream: 904.2 Kbps

ADSL Settings

VPI/VCI: 0/38
Type: PPPoA
Modulation: G.992.3 Annex A
Latency type: Interleaved
Noise margin (Down/Up): 7.1 dB / 6.5 dB
Line attenuation (Down/Up): 56.7 dB / 34.3 dB
Output power (Down/Up): 16.6 dBm / 12.5 dBm
FEC Events (Down/Up): 37216442 / 6
CRC Events (Down/Up): 83251 / 34
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
HEC Events (Down/Up): 561554 / 8
Error Seconds (Local/Remote): 1973 / 0
Click to expand...

Unless someone has a testable idea.
 
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Sorry, been away so unable to reply...

Well, you've got some quite variable Noise Margin figures there. It's possible something else is causing this interference, but I'm still erring towards a PSU problem. Virtually all PSUs these days are of the Switching Mode variety. If not properly designed and built with good suppression components, these can be a source of wideband electrical noise (interference). This noise can be directly radiated by the PSU, sent out down the mains power lead, and transmitted along Ethernet cables. etc. So you may not fully isolate the problem even if the XP PC uses a WiFi connection. If you have a spare PSU, it might be worth bunging it into that PC before you chuck it.

It might be worth also checking all your telephone connections and filter(s). Some of the filters and LJU plugs and sockets on the phone extensions are often of poor quality. This can lead to premature oxidisation resulting in poor, electrically noisy, connections. You are not blessed with a very fast Broadband connection, so make the most of what you've got. As a test, if you have the BT NTE5 type Master socket, remove the lower front panel and plug your router directly into the test socket. The test socket is revealed only once you have removed that lower panel, and if wired correctly, will have disconnected any other phones and extensions within the property. Whilst you have the socket open, just check that BT's incoming (2) wires are making a nice tight connection. Now check to see if you have increased the Downstrean Noise Margin figure.

Good luck.

ROGER - G0AOZ.
 
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Thanks for that Roger - If the PC was a bit younger I would try all your suggestions. I suspect you are correct & it is the PSU. BT were round a few months ago and checked all the wiring so I doubt it is that.

The observations that have me puzzled though are.

It does not crash the broadband when connected via ethernet and held at the BIOS screen.

It does not crash the Broadband when booted up but not connected in any way.

It does not crash next doors Home Hub 2 (Dads is a home hub 3) when connected via the openzone facility. But it will crash Dads Home Hub 3 when connected via OpenZone.

All is well when using the Windows 7 laptop - so that is what we will use for now.

If you can make sense of the above I really would appreciate it as may well some other poor soul in the future.

When I find the time I will bring it home and see if it crashes my Netgear router.
 
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I know its been a while, but I have been so busy you would hardly believe. Finally I have a moment to post this and bring this mini saga up to date.

I got a friend to run a scope over the offending PC and it was generating an awful lot of noise - +/- 1v of it on the 12 volt rail. Immediately suspected the PSU so disconnected PSU from PC and tested that just running a "cheat" so it powered up - no excessive noise.

Therefore suspected Mobo - Inspected all capacitors - but all look OK, no bulges, bumps or leaning ones.

Unless anyone has any ideas for a quick fix ( It is not worth replacing the mobo an ASUSTeK Computer INC. M2A-VM 1.XX ) It is for the dump v shortly - unless anyone wants a PC for testing purposes that can cause not only a BT Home Hub but also a Netgear DGN1000 to drop the ADSL connection if on the same mains circuit (No ethernet connection required!) The S.N ratio both in & out drops to zero and connection drops within 5 mins of powering up the PC!!!!
 
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PC dumped, video card salvaged and HDDs turned into ornaments!
 
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Thanks for the update on this problem. It's quite difficult to tell which part(s) of the electronic circuitry are causing issues without delving quite deeply into it with a 'scope, etc. Capacitors, for example, can still falter without showing any external signs. Some go open circuit, so in a suppression configuration electrical noise is no longer nullified. In the circumstances, binning this old gear is probably best!

ROGER - G0AOZ.
 
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