I use Google Chrome and had this same issue. I’ve had problems recently where I have to every time go into Google Chrome settings, click Show Advanced Settings, Change Proxy Settings, LAN Settings, and have to uncheck Use a proxy server for your LAN and the problems seem to disappear. I have to do this every time though. I kept getting this same error message, unchecked this under Chrome, and the game worked just fine afterwards. Not sure this will work for others, but it worked for me.