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Accidentally turned off my OpenReach modem. Fibre speeds dropped by 10mbit now.

OZ
Grafter
Posts: 43
Registered: 13-05-2013

Accidentally turned off my OpenReach modem. Fibre speeds dropped by 10mbit now.

Accidentally turned off my OpenReach modem. Fibre speeds dropped by 10mbit now. How do I revert back to my usual speeds? My usual download speeds are 6.2mbit and now I'm getting 5.2mbit. It happened after i accidentally switched off my OpenReach modem (plug), which was down for 30 mins.
28 REPLIES
Community Veteran
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Registered: 11-12-2013

Re: Accidentally turned off my OpenReach modem. Fibre speeds dropped by 10mbit now.

it may not be possible, its possible the SNRM reduced but not enough to disconnect, meaning the modem was hanging on with a lower attainable, and when you powered it off then you lost the speed.  If that is whats happened you are stuck.
NorthEasterner
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Re: Accidentally turned off my OpenReach modem. Fibre speeds dropped by 10mbit now.

You won't be 'stuck' with the new speeds. So the last post is inaccurate.
Your speed should return to normal over the next couple of days and gradually get better, or suddenly happen.
If not, you are not alone.  Raise a query @ https://faults.plus.net and should be resolved by an engineers visit or if possible, from Plusnet's side.
Regards
NE
Ex Plusnet Fibre customer. BT Infinity Customer using a BT Smart Hub. If you wish to say thanks, please click the thumbs up Thumbs Up
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Re: Accidentally turned off my OpenReach modem. Fibre speeds dropped by 10mbit now.

When I did the same it took a month to return  Huh
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Terranova667
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Re: Accidentally turned off my OpenReach modem. Fibre speeds dropped by 10mbit now.

Sadly your at the mercy of DLM Plusnet currently have no tools to hand as they do with ADSL so they cant simply get it back for you don't expect that to change any time soon either BT are being extremely slow in making changes to help consumers on fibre that's if they want to at all.
any way at present DLM will choose when to recover your speed  this can take days, weeks or even longer that's if it does it all,  just try not to have the modem go off again other wise you just make it worse. 
Community Veteran
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Re: Accidentally turned off my OpenReach modem. Fibre speeds dropped by 10mbit now.

Quote from: NorthEasterner
You won't be 'stuck' with the new speeds. So the last post is inaccurate.
Your speed should return to normal over the next couple of days and gradually get better, or suddenly happen.
If not, you are not alone.  Raise a query @ https://faults.plus.net and should be resolved by an engineers visit or if possible, from Plusnet's side.
Regards
NE

You never heard of crosstalk then?
He is unlikely to be DLM'd from a single power off.
I would put the chance at 95% long term loss of speed due to crosstalk, 5% due to DLM, DLM is very unlikely.
NorthEasterner
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Re: Accidentally turned off my OpenReach modem. Fibre speeds dropped by 10mbit now.

Cross talk is when a cable in the cabinet passes a signal onto a different circuit or cable. Like interference.
Crosstalk shouldn't have any role in OZ's issue.  If it does, then it should be resolved when the OP raises a fault if speeds aren't returned to normal.
The DLM can be incredibly sensitive, especially if the modem is disconnected. If the router is disconnected from the modem, it is not as bad.  If you need to disconnect for any reason, it is better to use th disconnect button on the router's user interface.
@OZ has the speeds improved since? If not, see what happens over the weekend and if no change, raise a fault with Plusnet.
Regards
NE
Ex Plusnet Fibre customer. BT Infinity Customer using a BT Smart Hub. If you wish to say thanks, please click the thumbs up Thumbs Up
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Registered: 11-12-2013

Re: Accidentally turned off my OpenReach modem. Fibre speeds dropped by 10mbit now.

north easterner you seem to be misleading him.
1 - crosstalk is very common on vdsl, to the point pretty much everyone has it.
2 - crosstalk is only a fault if it falls within openreach's fault parameters 25% speed loss within a short time period.
3 - if he is above his estimated speed and not over a 25% speed loss, its not a fault.
crosstalk reduces the available dsl signal, it can be reduced whilst the modem maintains sync so there is no speed loss as long as the modem stays synced, however if a modem resyncs after that loss of signal it will reconnect at a lower speed, for those of us who have unlocked modems this is very easy to see.
The DLM is not sensitive to the point a single disconnect will trigger it, in addition a router disconnect will NEVER trigger DLM as DLM only monitors modem disconnects and errored seconds.
The single piece of advise here is never ever disconnect your modem (unless you can see before the disconnect your snrm is above 6db), if you worried about performance.
NorthEasterner
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Re: Accidentally turned off my OpenReach modem. Fibre speeds dropped by 10mbit now.

I'm speaking from experience and if you power off the modem in the improper way which is just yanking out the plug, you will suffer a decrease in speeds.
Take the other day, I had a power cut for 8 hours, when my power came back the speeds for the Internet were ranging 10mb to 15mb.  This then gradually got back to normal.  This is the DLM in place monitoring your line.
However as I've been told by a BT engineer, all DLM's can work in a different way and can have different reactions to modem disconnections.
Upon googling crosstalk I found no clear answers on how crosstalk can affect speeds if you disconnect the modem.
Also can OZ not be a she? As you keep referring them as 'he'
Regards
NE
Ex Plusnet Fibre customer. BT Infinity Customer using a BT Smart Hub. If you wish to say thanks, please click the thumbs up Thumbs Up
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Re: Accidentally turned off my OpenReach modem. Fibre speeds dropped by 10mbit now.

Quote from: NorthEasterner
I'm speaking from experience and if you power off the modem in the improper way which is just yanking out the plug, you will suffer a decrease in speeds.

My experience is the exact opposite.
No matter how many times I powered off the Openreach modem, and turned it on again, I never had DLM intervene as a consequence, and never saw a change in speed as a consequence.
I don't advocate that you should power down much, but I've never had it impact me - even when playing around with filters a lot.
Quote
Take the other day, I had a power cut for 8 hours, when my power came back the speeds for the Internet were ranging 10mb to 15mb.  This then gradually got back to normal.  This is the DLM in place monitoring your line.

Depending on what you mean by "gradually", this is quite possible to be something other than DLM. DLM would only make changes once per day.
On the other hand, a power cut is likely to take out other properties ... and cause other modems to have lost sync. Possibly the DSLAM too (especially after 8 hours of outage). Things can be quite interesting when a lot of modems have to regain sync at the same time - from a position where all initially believe there is no noise. I've had one resync occur under circumstances that suggest no other modems were running at the time - the QLN graphs all showed a large drop in noise, compared with previous (and subsequent) syncs.
Quote
Upon googling crosstalk I found no clear answers on how crosstalk can affect speeds if you disconnect the modem.

It would have no direct impact whatsoever (unless, of course, you disconnect all modems at the same time).
There is, however, an indirect impact - which comes from the increased takeup in the days, weeks, or months since your last resync.
As already mentioned, the gradual take-up of FTTC increases the noise (from crosstalk) that your line experiences, so gradually decreasing the SNR value. Most of the time, your line stays sync'ed at the old speed, and survives this reduced SNR.
When you do eventually trigger a resync, whether automatic or manual, the speed attained will take proper account of this reduced SNR while seeking to keep a 6dB margin: This speed will be reduced.
When running speeds of the order of 70-80Mbps, a 3dB increase in noise would equate to around a 10Mbps loss of speed. On a stable line, a modem synced with a 6dB margin could probably withstand just such a (gradually incurred) increase in noise; certainly my (old) line kept working as the increase in noise gradually reduced the SNRM from 7dB to 4dB, until I eventually performed a power-cycle myself.
Plusnet Customer
Using FTTC since 2011. Currently on 80/20 Unlimited Fibre Extra.
Community Veteran
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Registered: 11-12-2013

Re: Accidentally turned off my OpenReach modem. Fibre speeds dropped by 10mbit now.

Quote from: NorthEasterner
I'm speaking from experience and if you power off the modem in the improper way which is just yanking out the plug, you will suffer a decrease in speeds.
Take the other day, I had a power cut for 8 hours, when my power came back the speeds for the Internet were ranging 10mb to 15mb.  This then gradually got back to normal.  This is the DLM in place monitoring your line.
However as I've been told by a BT engineer, all DLM's can work in a different way and can have different reactions to modem disconnections.
Upon googling crosstalk I found no clear answers on how crosstalk can affect speeds if you disconnect the modem.
Also can OZ not be a she? As you keep referring them as 'he'
Regards
NE

I am also speaking from experience, I am also not guessing, as my experience is from modems that show the true data, sync speed, snrm etc.
To give you an idea how DLM is in regards to disconnections, when I had my last fault I had over 10 disconnections in a 2 hour period and DLM left my line alone.
I suggest reading WWWombat's wise words.
thesawdust
Grafter
Posts: 384
Registered: 28-10-2013

Re: Accidentally turned off my OpenReach modem. Fibre speeds dropped by 10mbit now.

my modem was off for 2hours, i've dropped 7-8mb!
This isn't crosstalk for me, faults state no crosstalk found!  Wink
So yeah DLM can be very sensitive
jsm51
Grafter
Posts: 42
Registered: 20-12-2012

Re: Accidentally turned off my OpenReach modem. Fibre speeds dropped by 10mbit now.

I'm with chrcoluk on this one. Not that it's necessarily crosstalk on its own, but that the single event of powering off once is unlikely to be the cause. My line is partly aluminium and the max data rate varies significantly depending upon factors that I still don't understand. It can show a max data rate of around 20Mb/s and vary up and down between around 14 - 20 Mb/s. There is no apparent pattern to this but depending on when it re-syncs (often due to BT  TR069 activity on my HH5) the sync rate will vary by 5 to 6 Mb/s or around 30% of its max speed. Unless you are tracking this, the loss in speed may appear to be caused by the disconnection event.
I've also disconnected the OR and HH5 modem without any change in sync rate. My experience is also that DLM doesn't take weeks to restore speed when line conditions improve but that it will respond within a few days. Obviously if there are other issues and line conditions do not improve then DLM will not give you a higher sync rate.
thesawdust
Grafter
Posts: 384
Registered: 28-10-2013

Re: Accidentally turned off my OpenReach modem. Fibre speeds dropped by 10mbit now.

Hello,
well i guess DLM varies on different lines. It applied interleaving to my line (Speed didn't drop) now after my power outage for 2hours it seems interleaving was removed a few hours later but now my line has dropped speed.
It's been solid at 46/7mb for 12months plus but now at 40mb since interleaving was removed by DLM. Go work this out........  Grin
jsm51
Grafter
Posts: 42
Registered: 20-12-2012

Re: Accidentally turned off my OpenReach modem. Fibre speeds dropped by 10mbit now.

Yeah, I've no idea how the DLM algorithm is constructed but like you, I'm just trying to interpret from experience. I'm not sure why you'd want to respond to a single substantial disconnection with a cut in rate, whereas multiple short disconnections might suggest problems. Maybe there are some complex line conditions which affect it? Don't know.