Caddy and DDNS

[spetrillo]

My OPNsense firewall is behind my ISP router and setup as a DMZ host. I have setup DDNS on the ISP router, since it has the public WAN IP. This has been working for over 2 years. I now want to put a web server behind my OPNsense firewall, but I would like to use Caddy on the OPNsense firewall, for proxy and certificate management. Would it be advisable to use HTTP or DDNS for certificate issuance and management? In my mind's eye I would like to register the domain name, in this case *.petrilloconsulting.net, to Caddy and then use subdomains to identify the actual web services.