Try this (if you have not): Turn off ALL components in the network stream (i.e., everything that connects to or powers the internet, ethernet and Wi-Fi components of your system). Wait about 60 seconds and then power everything back up one at a time, starting at the source (usually the router/modem). IME, sometimes these various components just lose the “handshake” between them and stop talking to each other. It is often very difficult to nail down the culprit because, depending on the complexity of you network, the trouble maker is not always the same piece of kit. I hope I did not miss your point. Good luck.