I've not seen these symptoms described elsewhere. There are lots of discussion of "Server Not Found", but not as an intermittent problem. 1. I get "Server Not Found" on about 10-15% of my attempts to load websites. The error seems random, as there is no obvious pattern as to when and where it will occur. The same site might wor fine the first time and them the I get the error message if I try again a few minutes later, or vice versa. 2. The problem usually goes away with with a second click, but not always. 3. On a few clicks, the page only loads partially. 4. I've tested Waterfox and it seems to happen there as well. I don't have this problem with chromium. 5. Running Firefox 52, Win 7.