Something not quite right.

[#1]

Just to keep this thread up to date - I tried the Sumvision, but its configuration was so convoluted and unstable, I had to re-install the Netgear. Couldn't get the SV to keep PN's DNS servers, and the ones it had couldn't resolve any addresses.

[#2]

@Chris 1/2/3
Received my router this morning - thanks PN for the fast service 
Now I've got it, I'd like to install it where it would normally live and get rid of all the trailing wires downstairs. Have you got enough data from me with the test socket connection?

[#3]

Yeah that'll be fine, we can still collate data even when it's not connected top the Test Socket. If you continue to have issues, we have ask you to move the router back to the Test Socket though.

[#4]

OK thanks Chris. It will be tomorrow morning now as I'm out this afternoon and don't want to do swaps in the evening.

[#5]

I think the new router (thanks Chris H  ) has sorted the disconnects caused by the phone, but according to RouterStats Lite, I'm still disconnecting and instantly reconnecting almost on an hourly basis - although I'm not noticing it when b rowsing (is it possibly RSL mis-behaving?)  I've had I think one reset overnight, but I'm guessing that was because I initially reconnected at something like 11.5Mbps, which don't think my line can handle - I'm currently synced at 7948down/780up with an SNR of 16!! (thought I'd been put on 6dB)
If any of the DCT can comment on this, and provide my RADIUS log (please), I would be grateful.
I am away from home for 2 or 3 weeks from Wednesday 23rd, so there is no rush - the router, along with all other electrical stuff will be off until I return, but I thought it best to say thanks for all the help so far, and give whichever of the 3 DCT Chris's is watching this for me a chance to investigate.
I do have a couple of queries with regard to the TG582n, but I'm going to leave those until I return, I haven't got time to get my head round this tomorrow.

[#6]

John,
RouterStats - this does have some 'characteristics' which as you suggest you need to be careful about.
It can only report stats if the router responds to its queries.  I have seen the software report zero values (therefore imply a disconnect) when TG has been too busy processing error corrections, to reply to the admin interface on telnet or http.
The full product (might also apply to RSL) can loose a message between it and the router with the consequence that it is looking at the wrong message for its data.  Typically this results in zero value plots.  The test condition for this is to look at the content of the summary tab.  If this shows anything other than the router's stats then you have the problem.
It can sort itself out - the manual fix is to click stop and then start logging buttons.
Always be aware of the risk that what test tools tell you could be false, they are just like any other piece of software - error prone!

[#7]

Thanks for the confirmation of my thoughts on the subject - fortunately I've been around computers for many years, I was 'the IT department' at my employers when they first introduced computers for stock control and WIP. The proper IT guys were in an office 1.1/2 miles away and no-one else wanted the hassle  
By trial and error, I found the solutions you have given, but thanks for  the info.
I'm fairly certain I know the culprit. I'm running JD's Auto Speed Tester as a further check, and the blips show at the same time as JD runs - but not every time.

[#8]

Here's your connection graph that you requested:
<img src="http://community.plus.net/visualradius/generated/image13981731309064.png"/>

[#9]

Cheers Chris. 
I'll revisit this topic when I return from sunny(?) Brighton and tie up loose ends.