Things move fast on this problem ....
Ok people, let's see if we can summarise and reach some sort of consensus?
1) I believe that we are all agreed that it is (for the moment at least) hard to imagine how the PC's firewall would cause the router e.g. to drop the (PPP) Internet connection. So, we believe that as Ian said AVG is a red herring in this particular case. Other people are simply seeing AVG blocking their attempts to access the internet, not reporting a router dropping the PPP connection.
2) Although it's not entirely in the clear quite yet, the tests that Chrissie has done to date seem to have made it slightly less likely than it originally seemed that it might be EMI/faulty PSU or router per se.
3) Whatever exchange takes place between W8 and the router, it only seems to cause the router some difficulty when it happens during W8 load.
7LM, yes there is a considerable difference between W8 and previous Ws when it comes to loading. It no longer (I believe) has the hibernate option on closedown any more as in fact it
always hibernates when you close it down now, and in fact you have to go through some of the F8-style recovery options to prevent it from restarting from the hibernated image!! But on power-on load it differs from e.g. XP restarting from a hibernated image, in that with XP any driver changes would not take effect until the next cold restart. W8 on the other hand does what it calls a hybrid load, in that it reinitialises things like drivers so as to pick up changes. All this is just so much background on W8 (which I hope I've got right), and doesn't (I think) affect the issue.
However, W8 is
built around 'constant on' internet access - in fact as long as it has an internet connection it uses a Windows Live email address to authenticate the user's password. This can be changed (and may well have been in Chrissie's machine). To my mind this puts emphasis on the fact that W8 tries to establish an Internet connection very early in its load now, and I think it is trying to establish and in fact influence (i.e. configure) the router to ensure that this is present.
Here's a
hypothetical scenario. Please, anyone, feel free to take it to pieces.
Router is up with a running ADSL and PPP connection and most probably is already using its
own firewall configuration on the PPP connection. That just seems like common sense to me. Then say W8 comes along and asks/tells the router using upnp, 'please open these ports for me'.
Is it possible that if the router is willing to do this it might need to drop the PPP connection in order to apply the new router firewall settings as supplemented by W8? Could it be something like this that is causing the router to drop the PPP link?
Chrissie's live box is at least 6 years old I think she told us, and no doubt it's firmware is even older than that. I am not especially surprised that 7LM could not find a newer one. Of course Chrissie could ask Orange, but I fear they might be more likely to want to swap out her router than be able to offer a later firmware for the one she's got. I don't know how Chrissie would feel about that but I suspect she'd rather not, if at all possible. A lot has happened with upnp & Window's use of it in the last 6 years. It wouldn't surprise me at all if (assuming upnp is enabled in it) that the router didn't know what to do with some of the things it is seeing. They may not even be in the same format any more. Of course 7LM is right, it shouldn't cause it to fall over, but these things do happen, only too often!!
I personally like 7LM's suggestions. However, if he will forgive me, I would like to try them in reverse order.
I believe there is something called 'network discovery' in W8. I think it is designed amongst other things to find printers, routers, other PCs etc. I think it is this setting that drives a lot of (if not all) the upnp activity. So I'd like to try and switch that off first to see what effect it has, if any.
I'm not sitting in front of W8, so this is all vague memory, but: from the charms, select settings, then PC settings or maybe devices, but somewhere it has an option to switch off 'network discovery'. I'm sure a google will assist.
That would be my suggestion of what to try next. But, as I have already said, the more, and preferably better informed suggestions than mine, the better as far as I am concerned.
Finally, I do think that the OH is right in one respect Chrissie. I personally think you should be asking the builder to sort out this recurring W8 recovery rebuild you keep having. I don't think it is directly related to the router business, so I wouldn't even mention that to him, just this other thing. But whether to do that now, or after we get to the bottom of this router business, depends really on your patience and tolerance, and so it's your call.
Enough from me for now. What do others think?