Some notes on setting up a new Proxmox server:

https://pve.proxmox.com/wiki/HTTPSCertificateConfiguration

• Copy the tsig key to /usr/local/share/nsupdate.key
• Navigate to ACME plugins and create a new one:
  • ID: FreeIPA
  • Type: RFC2136
  • Key: /usr/local/share/nsupdate.key
  • Server: ares.jellybean.sihnon.net
• Create the ACME account via webui
• Create the certificate request using DNS type and FreeIPA plugin
• Order the new certificate

https://forum.proxmox.com/threads/proxmox-3-0-web-ui-on-port-443-instead-of-8006.13964/