1. It is most likely a network related issue from the Host. So please contact them and let them know of the same error message:
Failed to connect to yoursite.com port 80: Connection timed out
and let them know that it could be "network problem" issue.
2. Secondly it could also be DNS related issue, and Host will also be responsible for this as the WP site Host may have changed
to different server.
So, please Kindly contact your host regarding DNS, HTTP Loopback, firewall settings and Network based issues.
Once your network issue is resolved, then please try again to add the site.