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Having some random disconnection issues

milligan82
Newbie
Posts: 4
Registered: 19-03-2013

Having some random disconnection issues

Hi there,
Looking at the forum there are clearly lots of very knowledgable and helpful people here so thought I'd  pop a post up regarding my issue.
Basically it is random disconnects and I am trying to rule out all the usual suspects. Spoke to Plusnet Monday morning and we'd had 13 disconnects in 36 hours and seems to be getting worse. Started to degrade roughly three weeks ago. I am going to set up a different router with different filters and cables to the master socket to rule out any hardware issues. Just had a couple of general questions which wondered if anyone could help me with.
I have been trying to configure an event log on the router (a TP link TD-W8960N) to monitor the connection. Anything there I should be looking for as a potential issue, or for useful info?
We have also been maintaining a good speed and latency throughout the disconnects, about 2.3Mbps and 40ms ping which as we are fairly rural and a good couple of miles from the exchange seems fine. If there was noise on the line shouldn't the speed be dropping too? Or would that only happen with consistent noise on the line rather than blips? We had some quite prolonged speed issues just before Christmas and a BT engineer came out an tested both the line and the extension we use and said there were no problems and the line quality was actually very good.
Cheers for reading the post, any input or suggestions of things to try would be great,
Many thanks
8 REPLIES
Plusnet Alumni (retired) orbrey
Plusnet Alumni (retired)
Posts: 10,540
Registered: 18-07-2007

Re: Having some random disconnection issues

Hi there,
If it's a dropping connection issue there's not really anything useful the logs will show apart from how often it's dropping. Worth checking the line stats though to see if the SNR and sync speeds have changed as those would indicate a slowdown, which would be caused by the DLM picking up on the drops and adjusting the profile to make it more stable.
Hope that helps explain.
PeeGee
Aspiring Pro
Posts: 1,086
Thanks: 47
Fixes: 3
Registered: 05-04-2009

Re: Having some random disconnection issues

Have you seen this thread? It's about the W8961ND and repeated disconnects, but the 8961 has the Trend chipset, not the Broadcom of the 8960. I don't know if there are firmware problems, as I've just had a 5 month old TD-8816 v7 (Trend chipset) replaced as the down link SRNM would run at 6dB for a while, then suddenly describe a 2dB oscillation - though it didn't drop the connection - and then slowly drop from 4dB to 0.8dB before repeating Shocked
Plusnet Fibre (Sep 2014), Essentials (Feb 2013); ADSL (Apr 2009); Customer since Jan 2004 (on 28kb dial-up)
Using a TP-Link TD-W9980 modem-router.
milligan82
Newbie
Posts: 4
Registered: 19-03-2013

Re: Having some random disconnection issues

First of all many thanks for the replies, it is appreciated.
@PeeGee thanks for the thread link. I actually looked at updating the firmware on the router. If when I've switched routers for a while that helps with the dropouts I'll update the firmware on the TP Link to see if that has any effect. I'm trying to do my research on the various terminology and what they mean so I'm not posting lots of basic questions but still trying to get my head round it all. These are the current stats for my router:
Mode: ADSL_G.dmt.bis
Traffic Type: ATM
Status: Up
Link Power State: L0

Downstream Upstream
Line Coding(Trellis): On On
SNR Margin (0.1 dB): 89 61
Attenuation (0.1 dB): 585 337
Output Power (0.1 dBm): 0 129
Attainable Rate (Kbps): 3328 872

Path 0 Path 1
Downstream Upstream Downstream Upstream
Rate (Kbps): 2243 864 0 0

MSGc (# of bytes in overhead channel message): 59 12 0 0
B (# of bytes in Mux Data Frame): 70 108 0 0
M (# of Mux Data Frames in FEC Data Frame): 2 1 0 0
T (Mux Data Frames over sync bytes): 1 1 0 0
R (# of check bytes in FEC Data Frame): 12 16 0 0
S (ratio of FEC over PMD Data Frame length): 1.9967 4.0 0.0 0.0
L (# of bits in PMD Data Frame): 617 250 0 0
D (interleaver depth): 16 8 0 0
Delay (msec): 7.98 8.0 0.0 0.0
INP (DMT symbol): 1.24 2.4 0.0 0.0

Super Frames: 380954 343292 0 0
Super Frame Errors: 0 0 0 0
RS Words: 12381022 1884296 0 0
RS Correctable Errors: 161434 15 0 0
RS Uncorrectable Errors: 59363 0 0 0

HEC Errors: 0 862 0 0
OCD Errors: 151 0 0 0
LCD Errors: 2 0 0 0
Total Cells: 32566344 1619629 0 0
Data Cells: 8597926 16038 0 0
Bit Errors: 0 0 0 0

Total ES: 1047 4294967291
Total SES: 231 0
Total UAS: 64 4294967202
Am I correct in thinking that the SNR is a big factor in possible disconnects. The figure this morning went down to under 2dB which, if I've understood correctly, is not good and could lead to disconnects. Regarding this should it vary so much - if I've understood you PeeGee it should be a more stable figure. Also when routing around for answers (no pun intended) it appeared that the SNR can be changed, sometimes by the router and sometimes by the ISP with a trade off between speed and stability. Any input on this would be great.
@Matt thanks for the reply, regarding the SNR and sync speeds changing, changing how often? Do you mean after particular events or just if they are changing daily? Our sync speed still remains fairly consistent
Plusnet Alumni (retired) orbrey
Plusnet Alumni (retired)
Posts: 10,540
Registered: 18-07-2007

Re: Having some random disconnection issues

The SNR would only change if there was more background noise on the line or if the power of the signal from the exchange dropped (iirc - if I'm wrong on this no doubt I'll be corrected, not looking at anyone in particular *koff*anotherone*koff* Cheesy ) which might indicate a fault. Either of these things could also cause a drop in connection, but if the sync speed isn't changing that suggests things are alright.
milligan82
Newbie
Posts: 4
Registered: 19-03-2013

Re: Having some random disconnection issues

Thanks Matt for the SNR info, but that has confused me a little. If the SNR dropping (which it appears to be quite dramatically if I've got a handle on these numbers!) then that could be indicative of a line fault, but the sync speed being consistent implies there is not a fault. Have I got that right?
PeeGee
Aspiring Pro
Posts: 1,086
Thanks: 47
Fixes: 3
Registered: 05-04-2009

Re: Having some random disconnection issues

Your attenuation figures are very slightly better than mine (585/337 vs 605/365 {Thomson} and 619/375 {TP-Link}). However, your sync rate is 1543kbps below my current rate (I'm also on ADSL2 not 2+ and had 4Mbps before the recent rain Cry ) and SNRM 49 higher (figures presented in units used previously Roll eyes ). The SNRM variation may be due to a fault (line or modem) or a variation in some interference, but a 7dB drop seems a bit drastic - perhaps Matt could get a basic line test done, if it hasn't already. The last time that happened to me, the sync rate kept changing and a length of cable to the house was replaced - upping the speed from a variable 2Mbps Cheesy
Plusnet Fibre (Sep 2014), Essentials (Feb 2013); ADSL (Apr 2009); Customer since Jan 2004 (on 28kb dial-up)
Using a TP-Link TD-W9980 modem-router.
Plusnet Alumni (retired) orbrey
Plusnet Alumni (retired)
Posts: 10,540
Registered: 18-07-2007

Re: Having some random disconnection issues

More than happy to run a status check but it'd need to be done when the SNR is showing low on the router or it wouldn't prove anything, which could be tricky to coordinate. It'd be easier to test an alternative router (if milligan82 has one available) to see if the same issue is apparent with different hardware?
milligan82
Newbie
Posts: 4
Registered: 19-03-2013

Re: Having some random disconnection issues

Thanks for that. I'm just waiting delivery of an extension cable so I can connect the router up to the master socket but leave it in place, but when it arrives will be changing router/filter/line cable to rule out any hardware my end.
If before then I get a big SNR drop I'll post on the off chance you catch it and are able to run the line test, bit of a longshot but you never know!