Falling sync.

My sync rate has fallen for some reason over the last week. There has been
no change in my line stats:

Modulation:G.992.1 annex A

Bandwidth (Up/Down) [kbps/kbps]:288 / 5,472

Output Power (Up/Down) [dBm]:11.5 / 19.5

Line Attenuation (Up/Down) [dB]:26.0 / 42.0

SN Margin (Up/Down) [dB]:6.0 / 12.0

I used to enjoy sync in the upper 5 or lower 6 meg region with an IP Profile
of 5 and occasionally 5.5 Mbps. My router is normally on 24/7 but have
tried switching off for a few hours with no change. Upon daytime re-sync the SN
Margin is always around 12 dB even before the drop in sync.

Router (ST585 v6) is located at and connected directly to a master socket filter
faceplate.

Any suggestions please?

Which ISP? The 288Kbps is a little odd, and suggests possible wiring/filter issue. Remove the faceplate and check in the test socket.

THe drop in sync, suspect Down SN Margin was previously 6dB, with a 12dB target you lose sync speed to improve stability.

Thanks for the reply Andrew.

IDNet. Done the test socket routine no difference.

My SN Margin is always around 12dB at re-sync falling to around 6 at night but usually stays synced all night unless there are some noise spikes. Never had 6dB during daylight for years!

Time to monitor and if it holds connection at the 12dB target, then its wait a couple of weeks and system may lower you to 9dB target automatically. With 12dB the night resyncs should be less than you would have got at 6dB, and that is the key aim of the BT systems.

Does the upstream ALWAYS sync at 288Kbps - that would worry me more than the downstream, as suggests poor upstream performance, when this upstream should hold up a lot better as the line length increases.

In reply to a post by MrSaffron:

Does the upstream ALWAYS sync at 288Kbps - that would worry me more than the downstream, as suggests poor upstream performance, when this upstream should hold up a lot better as the line length increases.

No. Stats a few weeks ago on a good day:

Bandwidth (Up/Down) [kbps/kbps]: 448 / 6,880
Output Power (Up/Down) [dBm]: 11.5 / 19.5
Line Attenuation (Up/Down) [dB]: 25.0 / 41.0
SN Margin (Up/Down) [dB]: 23.0 / 12.5

So suggestion is some noise in the under 100Khz range is causing you problems, and may be the cause of resyncs.

Telephones and filters are the usual cause, or it is a sign that phone line is degrading, but alas would still be within spec if a remote check was carried out - probably!

Sorry for delay, had to go out!

Yes, my thoughts were that the line is degrading. Been a lot of rain recently but I would have thought the d/s attenuation would have suffered. I will check filter!

Well, would you believe! I have just disconnected a DECT phone that I bought about a week ago, rebooted the router and got this:

Bandwidth (Up/Down) [kbps/kbps]: 448 / 6,304
Data Transferred (Sent/Received) [MB/MB]: 1.90 / 13.07
Output Power (Up/Down) [dBm]: 11.5 / 19.5
Line Attenuation (Up/Down) [dB]: 25.0 / 41.0
SN Margin (Up/Down) [dB]: 22.0 / 12.5

Time to return the phone (assuming you're sure its not the microfilter at fault).

Just plugged it back in using an in-line filter (although I have a filter faceplate) and all still works OK.

Actually, although I said I bought it, I actually won it in a raffle!! Well, I bought the raffle tickets

Some devices benefit from double filtering which is what you are basically doing. It's rare though.

OK Andrew, thanks very much for your help.

AND it held the same sync rate all night!

Uptime: 0 days, 17:59:14

Bandwidth (Up/Down) [kbps/kbps]: 448 / 6,304
Data Transferred (Sent/Received) [MB/MB]: 39.57 / 691.76
Output Power (Up/Down) [dBm]: 11.5 / 19.5
Line Attenuation (Up/Down) [dB]: 25.0 / 41.0
SN Margin (Up/Down) [dB]: 22.0 / 12.5