According to this: https://support.chess.com/en/articles/9010617-why-can-t-i-connect-to-chess-com-when-other-sites-are-working-fine
One server to rule them all
Our current Live Server is literally one single server located in Virginia, USA - It is one of more than 350 servers that run Chess.com, with more on the way! This is our most powerful machine which has been fine-tuned to handle hundreds of thousands of connections at a time. That server connects out through the data center to the broader internet, and we use both Cloudflare and Google as the main bandwidth providers to send and receive traffic all around the world.
tried chess.com but came up blocked by cloudfare/ any ideas.