404 Error Https://remote.devtools.rocks

Maybe I am missing something but I can't really find much in the way of docs on how to get this to work.

I installed the extension by loading the unpacked extension into Chrome but when I click the extension icon it never gets to the 'copied' stage.

When I opened the background.html I see the xhr just looping with failed 404 request to remote.devtools.rocks/socket.io.

Is this no longer working?

or is there something I need to do or is there some way I can get a proxy running locally?

Rob