Hi all! Setup: I am running Linux Mint 18.1 with the standard 55.0.2 Firefox package. Problem: Every now and then I notice that Firefox runs into a string of "Server not found" pages with a variety of websites. Running Wireshark, I notice that Firefox simply does not send the DNS requests for periods of time. If I then ping the page name via the terminal, the name resolves correctly and provides the IP address. I can use the IP address in Firefox to get to the web page. Tried: Purging the package and installing fresh, and changing DNS servers. Neither resolved. Closing and reopening Firefox does not resolve even temporarily. Also, Chromium runs perfectly fine, so I do not suspect a system problem. Anybody have advice to diagnose? Thanks! Rex