My own fault...

[#1]

 
It's what I get for tempting the broadband gods, by saying my connection was super-stable and had been connected for a solid 9½ weeks. On Friday 8/11/13 at just after 5pm, my connection started going up and down like a lady of negotiable affection's unmentionables, until I powered off for 25 minutes, then I had to go to work.
Router logs show the connection stopped dropping around 10pm, and apart from a resynch on Saturday morning to improve the speeds, has been solid again since then.
My Current Line Speed does not appear to have changed despite all the reconnects, so I'm happy with that, however the connection speed when I got home on Saturday morning reflected it resynching at around 10pm the night before, so both downstream and upstream were well below their usual levels, hence the resynch at around 11am on Saturday.
Since then, touch wood, all has been OK, however I'm concerned that the (delayed?) Delta reports will cause the Current Line Speed to drop, so I will keep an eye open there.
Could I also ask for a Visual Radius log, please? I'm curious to see if the recorded drops match the router's log.

[#2]

ADSL or FTTC ?
If ADSL, try a new microfilter - I've seen these just die in the past and cause similar issues.

[#3]

ADSL, using SSFP so no microfilter to test. Connection has been OK since Friday evening so I don't think removing the face plate and using a filter would make any difference, but I'll look at that if I have another night like that.
@DCT - is there any chance of a Visual Radius, please?

[#4]

Hi Jaggies,
As requested:
<img src="http://community.plus.net/visualradius/generated/image13842419374114.png"/>
How are your speeds at present?

[#5]

Thanks, Chris. Speeds are fine and my Current Line Speed matches, as near as makes no difference, my IP profile (CLS 13Mb, IPp 13.06Mb).
The disconnections on Friday weren't as bad as I thought, a burst at just after 5pm until the gap where I powered off the router, and then a further burst either side of 10pm.
The disconnection on Saturday was me rebooting to get the synch rates back up, and all appears to be well for now.