I wonder if you want something similar to a question I asked a while ago: Setting up sites in Caddy when the DNS hasn't been set up yet
The solution to my question in that thread was the max_certs subdirective.
Since you are saying you are having TLS problems I’m guessing you want to start up Caddy even if a particular site’s TLS isn’t working at the time. The max_certs subdirective basically enables on-demand TLS so that Caddy doesn’t need to verify all TLS certificates on start up.