topic Re: Download speed dropped by ~20Mbps in Full Fibre

Download speed dropped by ~20Mbps

longedge — Wed, 01 Sep 2021 17:00:05 GMT

Until last Monday I was getting around 44Mbps / 8Mbps. I'm now getting around 22Mbps / 7Mbps. I also seem to have acquired a fixed IP as I can't make it change despite having disconnected completely and also re-started my session numerous times.

I notice that I'm not the only one experiencing a large drop in speed. Is there a general problem?

My current router stats-

Re: Download speed dropped by ~20Mbps

Mustrum — Wed, 01 Sep 2021 17:58:14 GMT

Your router stats show you are getting 48Mbps.

You noticing that other people having problems is not surprising given that's what most come on here for - unless they are your neighbours it's unlikely there is a connection.

Re: Download speed dropped by ~20Mbps

longedge — Wed, 01 Sep 2021 19:09:06 GMT

Yes, I'm synced at what is my normal rate in fact everything in my stats is how I would expect to see it BUT the speedtests that I've done on ThinkBroadBand, BT Perf Test and others all return about 22Mbps download. Until the day before yesterday it was consistenly 44Mbps (I'm on 55/10). I suffered a 20Mbps loss of measured download speed overnight.

It's almost as if I'm stuck on a failing gateway but my old habit of gateway hopping isn't working and I don't understand why my IP isn't changing after what must now be a couple of dozen re-connects.

Re: Download speed dropped by ~20Mbps

jab1 — Wed, 01 Sep 2021 19:23:29 GMT

@longedge t's almost as if I'm stuck on a failing gateway but my old habit of gateway hopping isn't working and I don't understand why my IP isn't changing after what must now be a couple of dozen re-connects.

Those 'couple of dozen disconnects/reconnects' over a relatively short period of time will be the reason you've lost speed - the DLM will have read this as an unstable line and attempted to stabilise it by reducing the speed and increasing the signal-to-noise ratio.

Because of the way IPs are 'localised' for Plusnet connections, it is possible to get the same one back regularly unless you stay disconnected for a longish time, especially if the local 'pool' you are on is fairly small, and other users are not changing, so not releasing a different one.

Re: Download speed dropped by ~20Mbps

longedge — Wed, 01 Sep 2021 19:52:40 GMT

My understanding of DLM is that it is repeated loss of sync that causes problems. Am I wrong? Does dropping the ppoe session and re-connecting trigger DLM intervention? I have actually re-booted my router i.e. lost sync as well a couple of times but that only since the drop in speed. The SNR I am seeing is exactly the same as it has been for weeks now, is that not a measure of whether DLM intervention has occurred?

If I lose sync then a re-connection takes approx 7 minutes. If I force a new session it takes between 1 and 2 seconds. In the past, more often than not a new session meant a change of IP but this has changed recently.

Re: Download speed dropped by ~20Mbps

jab1 — Wed, 01 Sep 2021 20:16:55 GMT

You could well be correct in your first paragraph, @longedge , but I don't know if that is correct for an FTTC connection - hopefully @Mustrum will come back and enlighten me - I admit my VDSL knowledge is at a fairly low level, but I am learning.

I can't comment on reconnection speeds - I had an almost 12 month uninterrupted connection with Plusnet and have lost it only once with my current supplier - and that was initiated by them to allow a router firmware upgrade, do will be ignored anyway.

As I say, if the pool of IPs yours is allocated from is fairly small , only a long loss of sync is likely to trigger a change of IP - out of curiosity, why would you want a new IP?

DLM certainly will have raised your SNR - to correct a fault, so maybe a deeper examination is required.

Am I correct in thinking this is a Fritz!box router? What is your current uptime?

Re: Download speed dropped by ~20Mbps

longedge — Wed, 01 Sep 2021 20:24:02 GMT

"why would you want a new IP?"

😃 TBH I don't particularly. I used to have one years ago but didn't need it so gave it up. It's just that I see the 'sticky' IP as something that has changed recently and wonder if it is an indicator to some people of where the problem might lie.

p.s. - Yes it's a Fritz!bOX 7530 and my current uptime is just a few hours. Previously it was around 14 days. Forcing a new ppoe session doesn't affect the sync uptime.

Re: Download speed dropped by ~20Mbps

Mustrum — Wed, 01 Sep 2021 20:25:09 GMT

If you were to run the advanced BTW speed test then we/you would see if it is congestion, rather than DLM that was slowing you down. DLM would also slow the sync speed, which has not changed.

It has been a while since I was a customer and did the gateway hoping trick, but like getting a new IP, since the new sticky network was implemented a longer line break, even overnight can be needed.

Re: Download speed dropped by ~20Mbps

jab1 — Wed, 01 Sep 2021 20:41:52 GMT

@Mustrum The 'attainable' throughput is somewhat higher than the 'current' - is that indicative of a problem? I withdraw my comment re: the SNR, as it may be a red herring - it is the same as mine, and I am running at near max speed on speed tests.

Re: Download speed dropped by ~20Mbps

longedge — Wed, 01 Sep 2021 20:49:40 GMT

BTW advanced test failed several times earlier on today with a message saying it couldn't proceed. I'll try it again now.

edit - still the same.

Summary of Performance Test

Timestamp

Wednesday 1 September 2021 | 21:47:4

Ping

22 Ms

Download

22.69 Mbps

Upload

8.49 Mbps

Summary Advanced Test

Your speed test has completed and the results are shown above, however during the test an error occurred while trying to retrieve additional details regarding your service. As a result we are unable to determine if the speed you received during the test is acceptable for your service. Please re-run the test if you require this additional information.

Re: Download speed dropped by ~20Mbps

Mustrum — Wed, 01 Sep 2021 20:47:40 GMT

@jab1 no, that is normal, although the difference to the actual sync speed may indicate a bit of banding.

But the lower speed test suggest congestion, either in the home or maybe exchange, but it would not be consistent..

No much detail shared so far, so will see what else is forthcoming.

Re: Download speed dropped by ~20Mbps

longedge — Wed, 01 Sep 2021 21:00:47 GMT

OK, well I'll give it a rest for now. At least the connection is still useable. If it's the same tomorrow morning I'll switch the router off for 3 or 4 hours and see if that makes a difference.

As far as congestion goes, I live alone and there's nothing running that hasn't been doing so for a year or two now.

p.s. I'm sure that my connection is banded (as I understand it), the estimated line length in my stats 735 metres is correct within a metre or two. The long re-sync times I see are down to the fact that my cabinet has vectoring, according to one of the engineers I had in a while back.

Re: Download speed dropped by ~20Mbps

jab1 — Wed, 01 Sep 2021 21:02:26 GMT

@longedge I attempted the advanced test on my (Zen) connection and got the same response on it - methinks it is broke.

Out of interest what do you get on (say) the Thinkbroardband test?

Re: Download speed dropped by ~20Mbps

longedge — Wed, 01 Sep 2021 21:23:16 GMT

Just tried - 22.6Mbps / 7.3Mbps interestingly the upload is pretty much normal.

Re: Download speed dropped by ~20Mbps

longedge — Thu, 02 Sep 2021 06:12:29 GMT

Service dropped around 01:30 hours and everything back to normal now.

Re: Download speed dropped by ~20Mbps

jab1 — Thu, 02 Sep 2021 06:17:34 GMT

Very strange - I wonder what caused that?

Re: Download speed dropped by ~20Mbps

RealAleMadrid — Thu, 02 Sep 2021 06:46:20 GMT

Edit... You posted while I was typing my reply, so whatever was wrong has corrected itself, maybe the line profile updated to the correct value when the line dropped overnight. You should ask Plusnet for a DLM reset to remove the banding, you could get the full 55Mbs sync if that was done,😀

@longedge Your router stats suggest that you are banded at 49Mbps with a high downstream SNRM of 11dB and the fact that this doesn't change when you reboot the router confirms it. You are correct in stating it is loss of sync on a connection that causes that DLM to take action. DLM would know nothing about the drops in PPPoE connection.

It looks like you may for some reason have been put on a static IP, you need to check the value of your Current Line Speed on the Broadband tab in your member centre account. This is not an actual speed but a profile which is supposed to track the BT Wholesale IP profile and is known to sometimes get stuck at a lower speed. It generally only affects users with a static IP but recently I have recently heard mention of a "Workplace Profile" that can restrict users' speeds, if this is the same thing I'm not sure, if you get no response from forum staff it may be worth calling customer service.

A profile of around 22Mbps is one that seems to occur frequently, possibly because it is the maximum value for an ADSL2+ circuit, why this would happen on FTTC is a mystery.🤔

Re: Download speed dropped by ~20Mbps

longedge — Thu, 02 Sep 2021 08:27:12 GMT

Now that I'm back to normal I have other fish to fry 😄.

I've been having similar problems for a long time although not as pronounced as on this occasion.

I used to make use of the Usergroup Gateway Checker and a change of gateway always resolved problems for me. Unfortunately the tool no longer works for me, I always get a "We can't identify the gateway" message. I'm now relying on my router to tell when I've managed to change gateway e.g. at the moment - 195.166.130.250 POP: acc-aln8.cd

Thanks to all for your interest & suggestions.

p.s. - re the banding, a lot of the infrastructure between me and the cabinet is very old so on a long line of elderly copper (and possibly even some aluminium) I quite accept it. I'm glad that DLM seems to have settled at 11dB. I have seen it as high as 15dB but every time in the past that it dropped I experienced constant disconnections.

Re: Download speed dropped by ~20Mbps

RealAleMadrid — Thu, 02 Sep 2021 09:15:21 GMT

If you are OK with the speeds you are getting and it's stable probably best to leave it alone and not change things.