Intermittent router disconnections

Hi all, I wonder if anybody can shed any light on this issue? I have recently moved from an up to 8Mg service onto a 21CN service. Whilst on the up to 8mg service I received a rock solid 6.8 Mg down and .5Mg up with no disconnections.

Since moving to the 21CN service I get 20Mg down and just over 1Mg up, marvellous I hear you say, and yes I am very pleased with my speeds. What puzzles me however is that sometimes my router will stay connected at these speeds for a twenty day period and sometimes it will disconnect and reconnect after only a few days!

The thing is when it reconnects it still reconnects at the same good speeds, there is no degradation in the service. Why could this be when this did not happen on the old up to 8Mg service? It never disconnected at all!

I have a decent router (Billion Bipac wired not wireless) and my line stats are these:
Mode ADSL2+
Upstream 1215
Downstream 23657
SNR Margin(Upstream) 6.3
SNR Margin(Downstream) 3.5
Line Attenuation(Upstream) 7.5
Line Attenuation(Downstream) 11.5

I only live 150 Meters from my exchange, any body who can shed any light on this conundrum?

Thanks.

I would guess that with such a short /low attenuation line, that you had plenty of noise margin left when you were on an 8Mbit/s connection, probably >10dB, leaving plenty of spare noise margin left to cope with any passing noise/interference. Your current 20Mbit/s connection is actually connecting at ~23Mbit/s and is pushing the capabilities of your line to its limits leaving little spare noise margin left to cope with any passing noise/interference.

1 discon per day or longer is nothing to worry about.

Can you tell if it is the ADSL that is discon or just the Internet. If the latter it could just be ISP's LCP Authentication Server that is playing up.

Damn those are good stats and speeds.

Also ADSL2+ uses difference frequencies too, some which maybe more susceptible to certain types of interference,

But on the other hand there could be an issue with the equipment at the exchange, have you checked for audible noise on the line ?

Quiet line test, dial 17070 option 2 using a corded phone in the test socket, (cover the Mic,or use secrecy button to prevent induction of ambient noise) all you should here is the recorded message , listen carefully for several mins,any crackles pops ect then you may have a PSTN fault ,Which should be reported to the company you pay line rental to
it's one of the first things most isp's will ask you to do if you report a fault to them ,

Thank you all for your comments, it's not really a problem because as I say when it does disconnect it reconnects at the same rate. I was just curious to know why.

I have tried the quiet line test on several occasions and the line is totally silent (to my ears at any rate) so I suppose it is just one of those broadband mysteries. My ISP is Zen by the way, what a fantastic company you might pay a bit more but it's well worth it!