Hello, have you tried clearing cache and flushing DNS as well? This could possibly be an issue that could be resolved by using a VPN.

Have you tried logging in with a VPN?

If logging in through puffin or VPN solves the issue, try resetting your router, otherwise, the issue resides with your ISP. The issue with the VPN is that it will slow down your internet speeds a large amount, but it helps to solve where the issue resides.