This kind of problem is sometimes related to DNS (Domain Name System) resolution. DNS translates website names into numerical IP addresses. Does using an IP address rather than a website name allow you to connect? For example, instead of 'google.com' use ' http://220.127.116.11/
'. If so, it's a DNS problem.
There can be several causes for this. Try rebooting routers or modems first. Clear browser caches and cookies. If still no luck, try a different browser. If still no go, contact your ISP. Sometimes the problem is on their end.