Route letsencrypt based on FQDN

Noob here. Is it possible to use haproxy to route the Letsencrypt service to individual servers for the purpose of upgrading their certificates? Say i have two servers:
www.domain.com
freepbx.domain.com
When its time to renew their certificates using HTTP, I want Letsencrypt to be able to access their well-known directories using their FQDN without my having to change settings on my firewall, etc.
I know haproxy can host (proxy?) the certs, but i want the certs to be updated directly on the two servers instead. Hope this makes sense.
Is this possible, and if so is there a tutoral somewhere to achieve this? Thanks for any help.