If you use something like Cloudflare for DNS then you have to use the raw IP of your server to connect via SSH, since Cloudflare will not proxy other ports besides 443. Cloudron also has rate-limits setup via iptables but those are hard to hit while manually trying to connect and after a short time your local IP will be able to connect again, so I doubt this is what you are hitting.
Also I am not sure what you mean by ping returning 0.0.0.0?