Thanks Andrew for such a speedy reply.
The BT man changed the master socket, ran some tests and said everything was fine between the house and the exchange. As I said earlier he suggested that Virgin National look at the circuit board at the exchange, whatever that is.
As for the connection, when the router is connected to either the master socket or test socket, it goes on the Internet (online), but then, mostly in the evenings, or sometimes at random times like 3am last night, the connection drops - the Internet light on the router goes red, the 192... page says 'stopped'. The DSL section of the router, quoted above, still shows as 'up' and the numbers (stats), but then, I think, during the 'disconnection phase', it can show as 'down'. I also noticed that this can happen when the both of us are on the Internet at the same time in the evenings, although there's no pattern to this, as it's dropped when I was browsing on my own. Initially, VM told us to change the password to a stronger one and then changed our profile from 'Fast' to 'Interleave'. When I click on the 'Check connection' in my Buffalo router, it shows cabling ok, but then it shows 'PPPoA server not detected' despite my using the PPPoA connection. So, I thought the router might be faulty, but then disconnections had occurred with another two routers, though I can't verify if any of the connection tests via the 192.... thingy showed there was no PPPoA server.
Now, the VM using Carphone Warehouse's network would perhaps explain why the both offer ADSL2+ speeds, whereas BT only offer up to 8Meg in my area. Carphone Warehouse (TalkTalk) also have capacity issues in my area, whether or not this has an influence on our problem, I don't know. We're connected to the Dalkeith exchange (EH22 3JN).
This is what the router says when there's a disconnection:
2011/10/15 13:17:48 PPPOE Wan IP 86.xx.xx.xxx obtained
2011/10/15 13:17:47 PPPOE pppd 2.4.3 started
2011/10/15 13:16:49 PPPOE Internet disconnected
2011/10/15 11:41:13 PPPOE Wan IP 86.xx.xx.xxx obtained
2011/10/15 11:41:03 PPPOE Internet disconnected
2011/10/15 11:35:04 PPPOE Wan IP 86.xx.xxx.xxx obtained
2011/10/15 11:34:53 PPPOE Internet disconnected
The PVC status has always been 'Down' rather than 'Applied', but I'm not sure if for Virgin Media it should be 'Applied'. Also, the stats never change, like the SNR margin etc. - they always remain the same, apart from slight variation in the speeds (between 18800-19000).
Thanks for your help and time.
Edited by edinburgh2011 (Sun 11-Dec-11 16:25:44)