thank you Mark Phelps. I have at last been able to install the controller driver, which has solved the problem. I did as you suggested, but there was a lot of trial and error before then, so perhaps I can pass on some of what I have learned along the way.
When I went to the Foxconn site I was faced with a long list of drivers, and although I knew by then that I was looking for a Lan and chipset driver there was more than one to choose from.Giving up on that, I went to the Advent site and looked at product support. It was then easier to find the drivers, and in any case I could have downloaded all the drivers on their list, knowing that the controller and chipset drivers would be there somewhere.
This is what happened when I downloaded a driver: I clicked on the file at bottom left of screen, which is where they all seem to be downloaded to.A page then opened up. If the file was a zip file, which it would say on it, then at the top of the page it would say 'extract all files'. clicking on this would unzip the sub-files, which would be displayed on the page.
if the file was not a zip file, the sub-files would already be displayed. I then scrolled down to the last few sub-files, where I found 'setup'. If there was more than one 'setup' sub-file I clicked on the one that said 'application'. Either way, the resulting instructions were easy to follow.
I would guess, then, that sometimes it is easier to go the pc manufacturer product support site than to the device site. Also, or at least in my own case, a zip file can be unzipped in the way that I did it, presumably the same with all windows 7 systems, rather than by using Winzip, which is not free.
Also, it seems, as Mark Phelps indicated, that there is always a 'setup' sub-file in the file list, which can be used to install the downloaded drivers.
Finally, it is worth pointing out that on my pc, and presumably the same with all windows 7 operating systems, there is a driver update facility. Open 'help and support'. in start menu.Enter 'driver update' in search box.Click on 'update your software, drivers or BIOS'. Then click on link to software and driver downloads. I hope that this will be a help to some people, so that they don't have to labour as hard as I did at solving the problem of finding and installing drivers.