Leave modem/router switched on - old wives' tale?

[#1]

I've been on ADSL for many years, and I've always switched my modem off overnight, without apparent problems. Recently I noticed that PlusNet, on various help pages, insist it is better to leave it on. So I tried it for a week. It made no difference to the DSL speed, as reported by the router, or to the download speed, whatsoever. So is this an urban myth?
PlusNet claim that if the modem is switched off, BT's automatic management will assume the connection is unreliable, and lower the speed. I can't believe BT's software is that dumb. How hard can it be to distinguish between (a) intermittent short term errors and glitches due to the line being too slow and (b) no response at all for hours on end due to the modem at my end being unpowered?
See http://www.thinkbroadband.com/faq/sections/radsl.html#303 - to quote:
One of the myths for the up to 8 Mbps and up to 24 Mbps services is that you should not switch off your modem.
Switching off a modem overnight, or if going away for a few days will not cause any problems with the training systems some providers use. The only time it may cause problems is if you switch the modem off and on multiple times in a short period, e.g. ten or more times in an hour.

[#2]

It may depend on the speed of your line.
It could be that you always connect at 8128 kbps or some other really high ADSL2+ speed, and switching on and off once a day doesn't matter.
Or it could be that after years of switching on and off once a day, the dynamic line management really hates you by now, has configured your line for maximum stability and minimum speed, and leaving the router on for a week isn't anywhere near enough time for the DLM to change its mind.
Without looking at your router stats, we can't tell if either of those scenarios might apply to you.
If you've got a line that will re-sync sooner or later at random, one extra re-sync per day probably won't help.

[#3]

ejs, my DSL line speed is 4544 kbps. Can I get at the router stats? If so I'll post them here. The modem/router is a Thomson TG585 v7.

[#4]

4544Kbps is a banded profile, applied when the DLM detects "very bad" instability on a line.
If you go here you should be able to find out how to retrieve the stats from your router.  I would imagine you could get a fairly substantial increase in speed.

[#5]

Thanks Barry, here's the results:
Link Information

Uptime: 0 days, 5:47:39
DSL Type: G.992.5 annex A
Bandwidth (Up/Down) [kbps/kbps]: 445 / 4,544
Data Transferred (Sent/Received) [kB/kB]: 0.00 / 0.00
Output Power (Up/Down) [dBm]: 12.5 / 0.0
Line Attenuation (Up/Down) [dB]: 22.5 / 42.0
SN Margin (Up/Down) [dB]: 26.5 / 12.5
Vendor ID (Local/Remote): TMMB / IFTN
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 0 / 0
FEC Errors (Up/Down): 0 / 0
CRC Errors (Up/Down): 0 / 335
HEC Errors (Up/Down): 0 / 223

[#6]

Quote from: ejs

Or it could be that after years of switching on and off once a day, the dynamic line management really hates you by now, has configured your line for maximum stability and minimum speed, and leaving the router on for a week isn't anywhere near enough time for the DLM to change its mind.

Looks like the above is what has happened. The quickest fix will probably be for someone from Plusnet to arrange an "SNR reset" for you, to have the dynamic line management forget all past history. That assumes there is no other problem, besides the switching on and off of the router once a day.

[#7]

With a 42dB attenuation I'd be expecting around an 8Mb download speed
My mother in law religiously turns their ADSL BT modem off *every* time they finish using the internet - their line profile is so messed up it's scary !
I've told her to leave it on but her argument is that as long as she can browse the internet, she doesn't care how fast it is. I've esitmated her modem costs between £5 and £10 a year max in electricity to keep on all the time.

[#8]

The truth of the matter is, it depends entirely on your line length and the local noise conditions along the length of the line as to what you may or may not get away with.
In your case raveydavey, not only does it look banded but I'd say you have some noise problems as well - that and constant switching on and off will be seen by the exchange DLM as a problem line, which is why you are either banded or limited by the Target SNRM which may be at 12dB.
For that attenuation line, on 21CN I would expect to see around double the speed you currently have without any line or internal wiring issues.
My line is the same attenuation and I can quite happily sync at 7582 & I'm on 20CN! But because of the way 20CN Profiles work (unlike 21CN) I don't bother to especially let it, as at 7456 currently I get more Noise Margin and the same 6.5Mbps Profile.
If I were to switch off regularly, and happen to switch on outside of daylight hours, I would end up with a lower sync speed an lower profile.
Edit: Incidentally, that TBB advice is extremely poor. If you have a dropping connection, you wouldn't need to switch off and on nearly as many times as 10 before DLM would act, because most people don't realise they have a dropping connection until they have been severely impacted by poor performance.

[#9]

Many thanks to everyone who has contributed to this thread, thanks also to PlusNet for their rapid response. PlusNet also comment that "... the advice in the community post you started is very accurate".
The reset has been done and my DSL speed is currently 6155kbps although as expected that is producing high error statistics. I will post here the result when things have settled down.
Link Information

Uptime: 0 days, 16:25:38
DSL Type: G.992.5 annex A
Bandwidth (Up/Down) [kbps/kbps]: 446 / 6,155
Data Transferred (Sent/Received) [kB/kB]: 0.00 / 0.00
Output Power (Up/Down) [dBm]: 12.5 / 0.0
Line Attenuation (Up/Down) [dB]: 22.5 / 42.0
SN Margin (Up/Down) [dB]: 25.0 / 4.5
Vendor ID (Local/Remote): TMMB / IFTN
Loss of Framing (Local/Remote): 12 / 0
Loss of Signal (Local/Remote): 1 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 20 / 0
FEC Errors (Up/Down): 0 / 2,157,655
CRC Errors (Up/Down): 0 / 1,278
HEC Errors (Up/Down): 0 / 1,162

[#10]

You definitely have a problem with that line or your internal wiring as 6155 sync with a 4.5dB SNRM is not good, never mind the CRC errors for the uptime.
Can you hear any audible noise on the line when using the phone or have any problems with incoming or outgoing calls? Who do you pay line rental to?
Where are you plugged in, at the Master Socket & is it an NTE5a? or an extension socket? Do you have hard-wired extension sockets, if so how many? Are you using any plug-in extension leads?
Do all your Microfilters look like this and is everything connected via a Filter?

[#11]

Thanks Anotherone.
Phone is fine, no noises or other problems.
Wiring is as follows: Master socket (type with removable lower front panel)  -> hard wired extension (about 5 metres) -> microfilter -> phone + modem.
There is one other hard wired extension, it is working but nothing plugged into it. I'm not sure how this is connected to the line.
Line rental goes to PlusNet.

[#12]

Does the NTE5a Master socket have the Openreach logo on it or the BT + Piper logo on it?
Don't disturb your modem/router or unplug it or anything for a moment as you've not long had a line reset, but have a look at the wiring on the back of the unused socket. Need to know what colour the wires are and what terminal numbers they are connected to. With a bit of luck you should have Blue+white trace on 2 and White+blue trace on 5. You may have Orange+white trace on 3 and White+orange trace on 4. Any differences in colours & terminals, say what they are.

[#13]

Thanks again.
The master socket has a BT logo like T ' ' , not Openreach.
Apologies if my use of terms was a bit vague - the extension is hardwired in the sense it's a fixture and uses proper solid core cable not flex, but it is fed by being plugged into the master socket. I can't check it at the moment without disturbing the modem, plus I don't want to break the no.1 rule of troubleshooting - never change 2 things at once!
After a few days it should become clear whether leaving the modem on makes a difference, then I'll look at other issues.

[#14]

Hi there.
I can assure you, leaving it a few days will not improve things - it's easy to misinterpret what can happen in the 10 day ADSL training period.
It's your unused socket I wanted you to look at, because it will give me an idea about the standard of your wiring, you don't need to disconnect or unplug anything to look at that & I still would like to know.
But from what you've already posted I can see what one of the problems is.
Are both extensions the same? Did you get them as a ready made up kit or did you wire the extension socket on the end of the cable yourself. Are the terminals on the Extension socket screw type or IDC type?

[#15]

Sorry Anotherone, we were talking slightly at cross purposes there.
Right, the extension in use (lounge) is plugged into the master socket. It was there when I bought the house, but I have relocated the extension socket, incidentally making it shorter. The socket has screw terminations, can't remember about the plug. I'm sure it had the colour/trace colour type of cable that you mention.
The unused extension (bedroom) is IDC, wires as follows:
1 none
2 blue
3 brown, green (2 wires)
4 none
5 orange
6 none
This I haven't touched, it was there when I bought the house.