I'm sorry. I will try to fill you in. Not sure what info you need but here goes. The error message occurs for any webpage I try to access. Five minutes later it may connect w/o a problem. I have checked and rechecked for firewall problems, malware, viruses, etc. I am using a wireless connection with a Comcast router/modem. As I said, another computer on the same network does not have error messages.
When I read some fixes, one is to got to Chrome settings, advanced, and change router settings but I am afraid to check or uncheck things that I am not sure of. If the other computer is working fine w/o error messages, I can't think it would be the router but maybe I'm wrong. Hope you can help.