Turn on the debug global option in your Caddyfile.
What do you see in Caddy’s logs?
You’re clearly having a TLS handshake issue, which might be because you don’t have a good certificate for that domain for Caddy to use.
I think you might have a mistake here, you used http:// but configured tls_insecure_skip_verify. Those are kinda in conflict with eachother. Is it HTTP or is it HTTPS?