With your actual internet conection, can you play other non browser online games?
Are you playing on a public internet like an office or school? games could be blocked there.
To find what is the problem you can try this:
Try to log in with another computer on your own internet, this is to find if the problem is on the internet configuration or in your computer itself.
If you have a laptop, try to log in with another network, if you are able to do it then it could be your router configuration or your internet service provider.
i have no more ideas for now.