Tom, I really love the HAProxy videos and the troubleshooting as well. I have followed them to a tee but it is possible after multiple tries, I am just missing something that keeps it all from working.
So I have a single backend server running (6) instances of Ghost blog on a single ip address at port 80. Each instance resolves correctly via their unique FQDN locally. In my internal DNS I have all (6) urls resolving to my WAN IP address.
Here is the link to the the dig requests dig.txt - Pastebin.com
My admin console is not on 443 and I have the webconfigurator redirect rule disabled.
Firewall rules in place for 443 and 80
My haproxy config is haproxy.cfg - Pastebin.com
I can access all (6) websites internally. This tells me that the HAProxy appears to be partially working. However, I can only access the ischeme and dg4u domains externally. Makes me wonder what is happening outside of my firewall. I have everything configured identically on DigitalOcean using their name servers. My register for the domains all point to the DO nameservers. But when I use 24/7 to check and compare websites I cannot get to my other (4) urls. Is this an HAProxy issue at all? Any insight by anyone on what might be going on here would be greatly appreciated.