What happened was the site's webhost decided to force SSL connections. It was supposed to be optional when the webhost enabled it. But due to some weird configuration issue on the webhost's side, it was not optional and all non-SSL http connections were redirected to https. Since there is no SSL certificate associated with this domain name, it just appeared to be offline or showed a connection refused error. While fixing it, certain parts of the forum were inoperable. Such as clicking on the menu icon (from mobile browsers), new user pages, anti-spam captchas, etc.)
This happened in the last two days. This should be fixed for everyone unless your browser is holding on to a cached copy of the site.