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Message 1 of 3

Help needed with recurring fault

Service and equipment details: ADSL2+ Broadband using OpenReach SSFP and Billion Bipac 7800N Router
We have a problem with our broadband, which is possibly a High Resistance fault. The original symptoms were that the phone line was a bit crackly on some occasions (but not too bad), and the broadband would drop out, reconnect, then immediately drop again.  This would continue for about an hour.  At some point, presumably after lots of action by the DLM, the line stabilised at a much lower speed.  I reported this fault on 14th April, and an engineer visited the next day. The automated test did not reveal anything (as it had settled down again), but he could see that things weren't right somewhere on his TDR. He said that the trace seemed to show several potential sources. He said he would go to the cabinet and check some wiring there, and that he would not need to come back to our house afterwards.  He also said that he would refer the fault to the underground team, as he was pretty sure the fault was underground and he was not u/g qualified. Unfortunately it appears that he disconnected our line at the cabinet about 4 mins later, and never reconnected it correctly, so I again contacted BT and we were without phone and broadband right over the week-end. On the Monday morning an engineer arrived and sorted it out. I only mention this for completeness, if a mod should try to understand what the various visits were for.
Our phone and broadband were great for approaching 3 weeks, but then the same started happening again. Either DLM or an engineer seemed to cause us to end up on a capped upload speed of 447kbps this time, where normally we would see about 1000kbps. I reported to BT that the fault was back, and the same engineer as the first visit came on 4th May. He said it didn't look as if the u/g team had done anything, and our line still looked the same on his TDR. The automatic test again reported no fault, but he again agreed that there was an HR fault somewhere, and that he would refer it to the u/g team. He said he could not reset our upload speed cap because there was no facility to do so if the test passed.  He said he would request a broadband reset via his report, but nothing has happened, and the fault was closed by BT.
Yesterday (15th May) the same thing happened again.  I noticed that our upstream SNR was at about 15db instead of the usual 22db (since the upload cap), and dropping fast. If I picked up a phone the upstream SNR dropped to around zero, then back to 15db when I hung up. This was repeatable.
This morning (16th May) the upstream SNR is back to 22db again. I picked up a phone and the upstream SNR went down to about 16db, then dropped to about 8db, returning to about 17db when I put the phone down.  All of this is repeatable (when the intermittent fault is there) with a different router (HomeHub 3), a different phone, and is the same whether I am connected via the OpenReach SSFP or via a microfilter direct into the test socket. My downstream SNR and speed have not been affected at all, and no downstream cap has been applied.
Because the effect on voice calls is minor to almost non-existent I am beginning to wonder whether this is a HR fault, or whether it is something on the ADSL2+ side at the exchange. I feel that it would be a great help if a forum mod could help out by taking on this fault, to liaise with BT/OpenReach and provide some consistency until the problem is resolved.
As the fault was fairly pronounced this morning I have attached a graph showing the upstream SNR variation during periods where the phone was off-hook. Also a graph to show that the downstream (rx) SNR is not affected.
I can provide modem stats if required, or further graphs from RouterStats, though it may be very difficult to capture the fault at its worst.
Please, please, can someone (preferably a forum mod) help with this?  We would very much like to get back to our normal service with an upstream and downstream target SNR of about 6db, and no further upstream problems.
upstream SNR.png
rx noise and sync.png
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Message 2 of 3

Re: Help needed with recurring fault

Hi @nigelg,


Thanks for posting. I'm sorry you're having problems. The stats you've posted certainly warrant further investigation. Can you please drop me over an email with your details? You'll get the contact the moderators link in my profile.





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Message 3 of 3

Re: Help needed with recurring fault

Hi @DavidM,

Thanks very much for your reply. I have sent requested details via the link.

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