Robert, I’m having trouble on mac, also. It all started for me last week or so… I forget now. Seems like it started right after I installed the 2019-003 high sierra security update.
You are getting the rate limits because caddy isn’t binding on the listen port but caddy keeps trying to renew.
I think my renewals had been failing for a while, but since the certificates were still valid, nothing was happening. but one of my domains was trying to renew with -1100 hours (that seems to me like it means that the cert expired 1100 hours ago. Since then, I moved the caddy working folder to a clean slate, and it fails ALPN for the first domain and the service fails.
I turned off “keep alive no matter what” so that I’d stop incurring a rate limit. I’ll try it again in the morning, but there is definitely something wonky happening on macOS with this.
Do you also run macserver?
See my thread here – Isn’t binding ports but not logging error either