Just posting this in case anyone else ends up in this same situation.
I had an interesting time tracking down why I couldn’t deploy - kept getting
SSH Error: data could not be sent to the remote host. Make sure this host can be reached over ssh.
This is just after I switched DNS to CloudFlare. I could still
ssh in via a terminal, and browse the site, but not deploy.
After 2 hours I twigged that
ssh email@example.com is the server IP, but the CloudFlare magic sauce was giving a different IP address to Trellis because my
/trellis/hosts file had hostnames. I switched these to IP addresses and bingo - faster deploys than I’ve ever had!
I first thought I was trying to be too eager and didn’t give the DNS time to propagate, but I could browse the site, so it mustn’t have been that. It’s the orange clouds!