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Has my throughput been capped?

fester
Grafter
Posts: 35
Registered: 21-02-2014

Has my throughput been capped?

My speed dropped over a month ago so I checked the router and it had resynced at ~2.4 Mbps. I use a Billion 7800DXL and it’s normally rock solid at 3.1/3.2 Mbps with a manual 1db snr tweak which gave me a throughput of roughly 2.6-2.7 Mbps. Without the tweak it synced around 2.5 Mbps which gave roughly 2 Mbps throughput. This happened for about a week last year, but it cleared by itself. I called tech support on 23rd June and found out my target SNR was set to 12db. The line was reset back to 6db and I gave it 11 days at default. No disconnects, but I noticed it dropped from 6db to 4db a few days in.
I started playing about with the router SNR settings yesterday and at 1db it was now syncing at 3.2 Mbps again, but still only giving a throughput 1.9-2.0 Mbps. I have now run tests at various settings and it seems I’m getting no more than this regardless of sync speed. See images below for samples and even though the BT test shows 2.15 Mbps it's actually never above 2 Mbps from external sources.
When I was with o2 I got 3.1 Mbps sync at default and 3.7 Mbps with the 1db tweak with this 7800DXL. It did cause a resync once or twice a week, but I had no problem with this as I was getting 3.2 Mbps (400 KB/sec) throughput. When I changed over to plusnet I put the drop in sync down to a change of equipment at the exchange or maybe a different interleaving config. It’s a long EO line and I’m happy to swap stability for speed so I would really appreciate someone taking a look. With no hope of fibre in the foreseeable future and this further drop in what is already a poor speed I’m considering something stupid like satellite bb  Cheesy
It has always been a very quiet line as you can see by the attenuation, but no crackling or any changes in volume. NTE5 master/faceplate filter with no extensions and I don’t have a phone (or any other equipment) connected. I swapped the faceplate filter and also tried a standard filter into the test socket with new cabling etc. Also tried a factory restore on the router and hooked up your Technicolor tg582n for comparison.
If you made it to here than thanks  Grin
7800 DXL @ 1db

7800 DXL @ 3db

7800 DXL @ 6db (auto)

TG582n @ 5db (auto) seems to sit at 5db even though target is 6db


50 REPLIES
Community Veteran
Posts: 5,057
Thanks: 426
Fixes: 16
Registered: 10-06-2010

Re: Has my throughput been capped?

It might be the Plusnet Current Line Speed (Plusnet's copy of the BT IP Profile). It should get updated automatically, or you can ask Plusnet to change it manually, perhaps try live chat.
fester
Grafter
Posts: 35
Registered: 21-02-2014

Re: Has my throughput been capped?

Thanks for the info.
I was hoping some kind member of staff on the forum could take a look at the situation. It’s not urgent and someone might even be able to get me back to the heady heights of a 3.7Mbit connection Cheesy
Community Veteran
Posts: 5,057
Thanks: 426
Fixes: 16
Registered: 10-06-2010

Re: Has my throughput been capped?

I see you are on ADSL1, although ADSL2 is evidently available, and might be slightly better, or worse. I think LLU o2/Be would have put everyone on ADSL2 or ADSL2+. Probably worth getting Plusnet to let you try ADSL2.
fester
Grafter
Posts: 35
Registered: 21-02-2014

Re: Has my throughput been capped?

I’m willing to try anything… even voodoo Grin
…you might be right though as I was getting 800/900 Kbps upstream sync with o2.
Also wondering if there is any benefit to using PhyR? It’s enabled by default on the 7800DXL.
Community Veteran
Posts: 5,057
Thanks: 426
Fixes: 16
Registered: 10-06-2010

Re: Has my throughput been capped?

PhyR is not supported by the equipment at the other end. It's a Broadcom proprietary feature, but you're connected to Infineon (IFTN). BT-based ADSL exchange equipment is either IFTN or TSTC. So changing the setting on your modem should make no difference, as it won't be in use anyway.
fester
Grafter
Posts: 35
Registered: 21-02-2014

Re: Has my throughput been capped?

Thanks again  Wink
Plusnet Staff
Plusnet Staff
Posts: 6,346
Thanks: 31
Fixes: 5
Registered: 26-11-2011

Re: Has my throughput been capped?

Hi fester,
I've just checked over your line and I can't see much wrong with it to be honest, that said, I've placed you an order to move your line from ADSL1 to ADSL2+ to see if we can get a bit more out of your line for you.
I'd expect for the order to complete by the end of the day on Tuesday. So, on that basis, I'd give your line a week or so from then for your line to settle back down, and hopefully you'll see an improvement.
If you encounter any other issues, let us know Smiley
Chris Pettitt
Cloud Environments Engineer
fester
Grafter
Posts: 35
Registered: 21-02-2014

Re: Has my throughput been capped?

Hi Chris. Thanks very much for that… fingers crossed  Smiley
fester
Grafter
Posts: 35
Registered: 21-02-2014

Re: Has my throughput been capped?

I noticed my router had resynced early this morning. I had a look at the stats and saw it was still an ADSL_G connection so I started messing around with the snr and rebooted a few times in preparation for the change to ADSL2. What I didn’t know was ADSL_G.dmt.bis is actually ADSL2 and the order had gone through early.
I noticed at 2db snr it was syncing around 3.1Mbit, but after me stupidly rebooting several times it’s now at 2.7Mbit.
Have I screwed up the 10 day training period and should I be using default settings?
Would it be worth resetting the line?
fester
Grafter
Posts: 35
Registered: 21-02-2014

SNR reset (and fix) request please?

I was recently switched to ADSL2+ which was great as it boosted speeds slightly. I was previously getting a max sync of ~3.2 Mbps and since the switch I got ~3.7 Mbps.
After the switch the SNR seemed to be at a default of 3db for some reason. After 10 days I tweaked the SNR so it sat around 1db and only had two resyncs over the next week. It then seemed to go back to 6db which was fine as I reconfigured the router to get back to 1db. Up until this morning there were no resyncs.
I’m guessing there was some sort of instability in the early hours as it’s now changed to 9db default. I can only lower the SNR by 5 so it’s currently at 4db now giving a sync of 2.7 Mbps.
Can someone please reset it back to 3db or even 6db? I would love it to be fixed at that setting too if possible as I would happily live with an occasional period of instability to get the much needed extra speed. If not, do you think running at 2db would stop it auto adjusting?
Previous post here:  http://community.plus.net/forum/index.php/topic,141185
Current stats are attached.
Community Veteran
Posts: 5,057
Thanks: 426
Fixes: 16
Registered: 10-06-2010

Re: SNR reset (and fix) request please?

The DLM monitors the error rate, error seconds rate, and I think it can even monitor the SNRM directly. It sounds like pushing the SNRM so low increased the error rate enough for the DLM to increase the SNRM. There wouldn't have necessarily needed to be any instability in the early hours, it would be just that the DLM decided to act after however many hours or days of a high error rate.
I think it was once possible to fix the target SNRM, possibly by setting custom DLM thresholds such that all possible values of MTBE and MTBR (mean time between errors / retrains) end up classified as Amber.
fester
Grafter
Posts: 35
Registered: 21-02-2014

Re: SNR reset (and fix) request please?

Thanks for the info… fingers crossed something can be adjusted. Even though it only gives an extra half Mb throughput it’s 20% more at my modest speed  Cry
cedlor
Grafter
Posts: 685
Thanks: 2
Registered: 02-04-2015

Re: SNR reset (and fix) request please?

Not that I know much but on your stats it says  mode is   g.dmt.bis   which I think is ADSL2     Not  ADSL2+ which  would be g.dmt.bis+  
So maybe it has switched back. ( Unless the router is reporting it wrongly)  IF it was ever put on ADSL2+ 
fester
Grafter
Posts: 35
Registered: 21-02-2014

Re: SNR reset (and fix) request please?

I was told it was going onto 2+ (see previous thread) but it has been on ADSL_G.dmt.bis since the switch. Not sure what’s better at my attenuation, but I’m willing to try anything if it might help Cheesy