Line Problem

Not sure I can do anything apart from relay my experience.

My line is poor (an underground line just dumped in a 1960s estate and neglected by BT ever since though in fairness there is no access to it. So with the hardware falling to bits after 50 years we have to rely on software to try and compensate). When I investigated routers (FTTC) the Fritz seemed best at coping giving me in excess of 30 Mbps down and 6Mbps up, much better than the BTw forecasts. For the last 5 years the line has been good with minimal latency spikes, even with streaming and minimum latency below 8ms, with negligible packet loss except on the rare occasions when there have been problems on the IDNet network. But in the last few days streaming became near impossible and BTw tester said i should report a fault after the Tap3 test came up with 6 Mbps down and less than 600kbps up. But on reporting a possible fault to IDNet they are only interested in selling me their standard router.

The Fritz has three adjustments 1-4 (between stability and max speed) for SNR, INP and RFI. Any ideas which I should adjust and where to reduce latency and improve streaming? I presume at least the SNR (presently between 6 and 8 at max speed) , and probably the INP both too starting at midway level 2 of the 4? The modem has been restarted (by me, deliberately) a lot over the last few days, for troubleshooting, so I don't want to adjust too often and start DLM kicking off to make matters worse. Otherwise it holds the line well, for months on end. None of the reported stats except for speeds have changed.

I think the Fritz! line management software still improves the line: without it using the OR modem and a standard cable router shows on TBBQM a consistent 40-60% packet loss. With it, the packet loss disappears, minimum latency more than halves (down from around 25ms to below 10ms), but there are still regular latency spikes of up to 120ms+. (Both, when the connection is not in use, with nothing connected other than the router). Uploads improve though with the OR modem. IDNet say my line passes their test and is therefore acceptable and nothing can be done.

I know I'm stuck and changing ISP is my only option. Any cheapn'cheerful could not be any worse, surely. Bit disappointed, though. I hoped for better with their Fibre Pro, which is useless on my glorified ADSL.

I've ordered the latest Fritz in case the router has just clapped out but I can see no evidence of it.

Edited by deleted (Thu 05-Nov-15 12:02:56)

If the issue is the VDSL part of the line then this will remain the same even if you change ISP so if that is the problem it won't help.

Restarting a modem a lot on FTTC increases chances of DLM slowing you down, what are the line stats showing, if its poor copper then you should be seeing poor SNR margins and wildly varying sync speeds, if sync is perfect but getting packet loss and no large amount of errors across the VDSL then you may be looking at a congestion issue, and this generally follow a timed pattern.

Does the phone work?

From the Fritz! (assuming it's working OK) sync is utterly consistent apart from the sharp (6am drop a couple of days ago when the problems started) one time drop in upload sync from 6Mbps to 600kbps). Zero errors or 1 a day). Prior to then there was no material packet loss or latency spikes ever, for years, even when streaming.

The Quiet Line Test is perfect, connected to the main socket. No issues with using the phone.

Stats from Fritz:
Negotiated Connection Properties
Receive direction /Send direction

Max. DSLAM throughput kbit/s 40000/6000
Min. DSLAM throughput kbit/s 128/0
Attainable throughput kbit/s 40312/660
Current throughput kbit/s 40000/600
Seamless rate adaptation off/off

Latency fast/fast
Impulse noise protection 35.3 /44.3
G.INP on/on

Signal-to-noise ratio dB 8/6
Bitswap on/off
Line attenuation dB 21/22

Profile 17a
G.Vector off/off

Carrier record B43 /B43

Error counter
Seconds with errors (ES)
Unrecoverable errors (CRC)
many Errors (SES) per minute
Last 15 minutes
FRITZ!Box 5 0 0.01 0
Central exchange 0 0 0 0

Using the OR modem and a different cable router for a few hours yesterday afternoon however the upload sync seemed to have increased back up to 6Mbps, with massive packet loss: see the TBBQM link here (the solid red is when the Fritz router was switched off before I swopped routers/modem]:
My Broadband Ping
and after I swopped back to the Fritz todays with just the Fritz here: My Broadband Ping

The practical issue is the impossibility of streaming without constant buffering.

For comparison a busy day with streaming just before it happened is here:
My Broadband Ping

And the following day my line fell off the cliff is here:
My Broadband Ping

The change of ISP I'm thinking of is to A&A because of their line quality monitoring designed to identify and help deal with this sort of problem? IDNet are offering a test router, which I gather is a necessary pre-requisite if BTOR get involved. But they'll charge anyway, unless you have an ISP prepared to argue the toss furiously (hence A&A)? The alternative cheap n'cheerful suggestion was on the basis it's pointless paying IDNet premium price (or even VDSL) for a rubbish line suitable to browsing and basic email only?

Edited by deleted (Thu 05-Nov-15 21:57:01)

The very low upstream sync is a sign of a problem and if another modem gives the sync then suggests either a dying modem in your normal kit, or a change to line operation your normal modem does not like e.g. G.INP switching on

That's what I thought might be the case, but why does the horrible continuous packet loss then suddenly appear (instead of the latency spikes) when substituting with the OR modem and a different router?

G.INP was switched on a couple of months ago and improved sync, and virtually eliminated reported errors (still the case).

Edited by deleted (Thu 05-Nov-15 22:13:46)

No answer for why the packet loss when back on the OR modem, which router is doing the PPPoE at that point?

What is odd is that the packet loss is happening when there is otherwise good latency performance, usually see a bit more yellow due to variance, i.e. packets corrupted and then retransmitted before the ping timeout.

In reply to a post by MrSaffron:

No answer for why the packet loss when back on the OR modem, which router is doing the PPPoE at that point?

A Cisco/Linksys WRT120N. Will try later with a Netgear WNR1000 (supplied by IDNet), but that is presently in use on the backup Fixed Wireless connection.

UPDATE: The good news is I can stream consistently on the Netgear. So many thanks, your theory about the modem going up the spout looks spot on. Pity as it's one month over the 5 year warranty period!

Just one thing occurs to me, could the Fritz QoS significantly be lowering the minimum latency to maintain download speed and could that be messing up the connection and might just adjusting the settings (which? SNR and/or INP, though presumably not RFI??) to improve quality and lower speed make a difference? I'm not sure why it might be doing so now but wasn't before (although there was a recent firmware update, which I think introduced the additional adjustments to INP and RFI). Otherwise I suppose there could be a change in software at the DSLAM or just line deterioration with the onset of colder wet weather.

But the Netgear although with the higher minimum latency has less and lower latency spikes (yellow) and a small (1-3%) packet loss, so much improved on the Linksys.

Many thanks again. As you can tell, it was eating at me!

Edited by deleted (Fri 06-Nov-15 15:00:27)

Lowering latency is not something a setting trying to optimise download speeds would be doing.

QoS should not affect VDSL2 parameters, but if you are using the Fritzbox line quality parameters to try and tweak the VDSL2 then you are into experimental areas as the Openreach DSLAM tends not to tolerate attempts to force stuff on it, i.e. its more locked down the old ADSL2+ kit (which was ran by different people)

Several Fritz!Box users have reported a significant reduction in upstream sync around the same time over on Plusnet: http://community.plus.net/forum/index.php/topic,1453...
Mine has dropped from 20000 to slightly over 2000.
When I dig out my OR modem (if I can remember where I put it) I'll try using it with the Fritz!Box.
This appears to have happened on both Huawei and ECI cabinets and on more than one firmware version (06.20 and 06.30 at least), not sure if all are the same model of Fritz!Box (mine's a 7390).