seglea

Thank you for the very helpful posts here. I found similar suggestions elsewhere on the web, but not so clearly put. However, they didn't solve the problem for me. I tried a couple of other things, including giving my network adapter a static IP, but that didn't work either. In the end I bought, for just under £10 (=$15 US) a new PCIe (network adapter) card. I couldn't replace the one already in the machine, because it was built in to the mother board, so I just disabled it throught the Device Manager after I'd plugged the new one in. I did have some reason to be suspicious of my existing PCIe, because it has always been random as to whether it registered on the network switch as running at 1Gb (which it is supposed to) or at 100Mb. Anyway, replacing it seems to have solved the problem completely. I could have used a USB to RJ45 adapter (costs 3 times as much, though) if I'd not been happy going inside the machine - but I'm an old guy and we used to have to do that all the time, so it doesn't bother me. Having read posts all over the web, and the feedback on them, my view is that if you have this problem, then if it is due to software or the state the network has got itself into, the suggestions above are likely to fix it, and nothing else is likely to. If the suggestions given here don't work, it may be a hardware problem - and the hardware fix is cheap and easy.