Comment by ivanr

As already noted on this thread, you can't use certbot today to get an IP address certificate. You can use lego [1], but figuring out the exact command line took me some effort yesterday. Here's what worked for me:

    lego --domains 206.189.27.68 --accept-tos --http --disable-cn run --profile shortlived

[1] https://go-acme.github.io/lego/