Thank you for all the comments. I decided to join Sky Broadband and Anytime Talk and have just put my order in.
I'm really going to miss Zen they have been fantastic, but I needed to consolidate all my services in to one package and reduce my monthly bill.

Once you are online with Sky please please update us. I am sure it's going to work well for you but it's always good to hear.

As a side note. Sky run DLM which is different to other ISPs. It doesn't set a noise margin target but a sync target.

Sky DLM is very strict. It aims to get you on a speed which means the line will not drop. Most ISPs will allow a sync where a line drops once every day or so. Sky aim for total reliability, they do not want a single drop out ever. It's not uncommon to see a Sky line with a connection time of 100+ days without a drop out.

This also means that customers using poor quality phone extensions in their house, or not in the master socket, who have experienced constant drop outs on o2, BE, BT etc... These customers will see a slower sync on sky but crucially their line will not be dropping out. The customer things 'it must have been BT.' It wasn't, it's their bad setup but Sky can somewhat cover this up more than others.

What this means is that you really really need to get the DLM right. It runs for the first 10 days and sets a speed. It may set your line to say 10Mbps. In this case you almost always sync at this speed.

If your setup is right, e.g. in master etc you will see similar speeds to on other ISPs. If it's wrong, you're gonna be slower.

Whilst DLM runs do not unplug the router at all. Just leave it well alone. This way you will get the best speeds.

DLM usually starts you off at 4Mbps, it then monitors the line for a while before increasing the sync (usually around 1 - 3am). At the end of the 10 days it will fix a speed which you can see in mysky. Usually this speed isn't the best speed in the world but it's extremely stable. If your line is near perfect you will see a 3db SNR and a great sync (most people don't get this 3db SNR, they see a slightly slower speed, with a 6/7db SNR).

Over the coming months DLM will keep a close eye on the line. If it's extremely stable DLM will kick in again and you are likely to see even better speeds. For this to occur you need to be keeping the router on 24/7 really.

Best of luck and just remember to keep it connected as every time you switch off it sees as a drop out and sees it as instability.

Edited by ukhardy07 (Thu 18-Jul-13 16:39:46)

In reply to a post by ukhardy07:

I would bet my life the sky line would then have the good pings and not the BT one

Well, I hate to tell you but they have been swapped. I'll allow you to rescind your bet

The Sky line has actually been at least two wire pairs now and two ports at the cabinet and exchange. More has gone wrong with my Sky broadband than I have time or memory to reiterate here.

The sky line was swapped, it was still not put down the exact line that the BT line is using. The two are not comparable therefore.
If it had been both lines would be very similar

On fibre line managements the same on all most ISPs.
Also it's important to note that a line fault generally is not isp specific. It sounds as though sky have been trying to atleast rectify the issue.

99% of times a line fault with sky would be a line fault even if you switched to BT or talktalk on that line.

I think you are an isolated case where your sky connection happens to be coming down a bad line. Granted perhaps sky should have resolved this better.

In reply to a post by ukhardy07:

...... It's not uncommon to see a Sky line with a connection time of 100+ days without a drop out.

Best of luck and just remember to keep it connected as every time you switch off it sees as a drop out and sees it as instability.

It all sounds very good, similar approach that BT have, just a different way round, so as long as the line is stable the best thing for both systems is to have a a small UPS.

Minor mains cuts always trashed my profile when I was on BT, went with O2 in 2007, resync always around 55-5900 no worries, so have decided to wait and see what happens at transfer time to SKY. Longest uptime with O2 -63 days-, with BT 42 days. Always power cuts.

SKY though does appear to have some DLM issues, been following SKY's own forum, to get feel for how they do things, some users have never got above 4meg, even short line as their line is stable the DLM never kicks in, sounds similar to BT's "stuck profiles". Quite a few ex O2ers as well,

It's possibly due to error build up.
I've never seen it get stuck at 4 meg. It can often take 5 or 6 days before the sync gets increased.
I think those stuck at 4 meg have probably been disconnecting the router / changing router settings causing a reboot and resync during those few days.

If DLM sees too many resyncs even on a line that can easily handle 20Mbps it won't increase from 4. I have found DLM to be extremely sensitive. Just one or two resyncs in a day can stop it increasing your speeds.

You never know the full story. I doubt you'll experience any major issues.
When I say uptime I am referring to actual time being synced. Not router uptime.
The router can be on for 100 days but may have dropped sync 20 minutes ago.

Edited by ukhardy07 (Fri 19-Jul-13 13:26:03)

In reply to a post by ukhardy07:

Just one or two resyncs in a day can stop it increasing your speeds.

When I say uptime I am referring to actual time being synced. Not router uptime.
The router can be on for 100 days but may have dropped sync 20 minutes ago.

Thats why I'll get a UPS, the power only goes for about a 1/2 sec but does it about 20 times in 1/2hour. Then can be OK for weeks and then couple of times week.

Actual sync time 63 days, no LOS, LOF, LOP, LOLink. back to work for now. Cheers

In reply to a post by ukhardy07:

The sky line was swapped, it was still not put down the exact line that the BT line is using. The two are not comparable therefore.

Thanks for that information.

I realise I'm not giving you all the details to prove it QED but please just take it as read that I probably know my setup and/or the BTo guys (3-of) who spent nearly three days here do.

I'm not knocking Sky, for the price, but you do get what you pay for.

I do understand you.

Fact is a sky fibre line and a BT fibre line would behave almost identically if they had the same line under the same conditions. Obviously the networks are slightly different but DLM interleaving etc would perform the same way.

Evidently the lines are different, it's not comparable. It's not the isp it's the line. If you were on any ISP with the problematic sky line the same issues would occur.
It's probably not satisfactory that sky haven't resolved them entirely which another ISP may have done better.
Sky do not limit every customer or cause problems to every customer because they are cheap.

FTTC is installed and managed at the fibre cabinet by openreach. All ISPs get the same treatment here. The only line management is at the cabinet and again all ISPs are treated equally here.
Line management is responsible for interleaving etc which in then affects pings.
Clearly it set a higher interleaving depth than the BT line. The only reason for this is that the Sky lines got bigger error build up, perhaps slightly longer, worse grade cable, possibly much more crosstalk than the BT line. This is all physically the line not the isp. Yes they tried different ports etc but its still not a like for like.

I appreciate your bad experiences with sky I really do. They should have resolved this better. Nonetheless you were just unlucky with the bad line

In reply to a post by ukhardy07:

Line management is responsible for interleaving etc which in then affects pings.
Clearly it set a higher interleaving depth than the BT line. The only reason for this is that the Sky lines got bigger error build up, perhaps slightly longer, worse grade cable, possibly much more crosstalk than the BT line.

I thought this was interesting as one of my friends has a BT line and the other a Sky line both with very similar attenuation.

The Sky DLM has a sync of 9Mb and has set a 3db SNR and applied significant interleaving to eliminate errors on the line whereas the BT DLM has opted for an 8Mb sync and a 6db SNR and removed interleaving but incurs quite a few CRC errors. Both lines perform well and I doubt either friend would move from their respective ISPs.

Thanks
Tim